This was the killer night - the first time she could flash her ID and move past the scrutiny of nightclub bouncers to soak in the club scene legally.

But a Monday? What a disappointing accident of birth.

"We couldn't pick the day of the week," said Musso's friend, Jess Honaker. "We had to go with it."

But on the day itself, the five girls drove the 160 miles from their York, Pa., home, and by nightfall they stood in line between other Atlantic City partygoers, trendy in their off-shoulder dresses and spike heels, waiting to descend an escalator into subterranean darkness.

Down there - below the casino floor and away from the flashing lights and loud noise of slot machines - is Borgata's nightclub mur.mur, a symbol of clubbing and nightlife in Atlantic City. With internationally known DJs, crops of celebrities and million-dollar investments made in the designs and furnishings, mur.mur and other Atlantic City venues now offer something for clubbers every night, all night, on a level with some of the largest cities, their promoters contend.

And clubbers are responding, flocking to Atlantic City where they spend lots of money, and many hours, in search of a good time.

As the now 21-year-old Musso put it: "We might not come out till dawn."

Outside the norm

Sitting in his New York office, club consultant Ricky Greenstein compares Atlantic City's nightlife favorably with club scenes on the West Coast and on his doorstep.

"There has been an explosion in the scene down there (in Atlantic City)," he said.

Greenstein does not run clubs. Instead, he and his company, Moodswing360, are hired to help book DJs and promote events, using viral marketing. He first worked in Atlantic City with mur.mur, which opened three years ago, and now works with a variety of city venues, including The Chelsea Hotel.

Packed clubs over weekends are expected. What Greenstein has been watching closely is the rise of a locals-driven midweek scene. Much of the midweek crowd consists of resort workers out on industry night. However, those packed dance floors have become a marketing tool - as Atlantic City visitors show up during the week and find the scene buzzing like a weekend night.

"They might look surprised when they walk into these places," Greenstein said of unsuspecting tourists.

Musso and her friends had happened upon Mondays at mur.mur, one of two clubs inside the Borgata Hotel Casino & Spa. But they could easily have done the same Tuesday - at the newly-opened Dusk, inside Caesars Atlantic City. Or Wednesday, at the Harrah's Resort club, The Pool. Or Thursday, at two local venues - Providence at the Tropicana Casino and Resort, or at The Chelsea Hotel's fifth-floor club, C5.

While other resort clubs had gained a following among gambling clientele in the past, the launch of mur.mur, in 2006, marked the moment when the Borgata rejected every stereotype associated with casino nightclubs.

"From the start, I think as far as nightlife, we weren't interested in what the 'norm' was here in Atlantic City ... just a big, square box with slot machines and a bar," said Gregg Coyle, director of nightlife for mur.mur.

Borgata opened mur.mur shortly after its first club MIXX, showing a belief that nightlife crowds could fill a second space, said Coyle - if that space had state-of-the-art turntables and a budget of thousands of dollars to book each high-profile DJ.

Because tucked in the booth with a stack of vinyl records and once almost anonymous, DJs have risen to command the salaries and crowds once reserved for major rock stars. Their names are the draw for clubbers, and mark nightclubs apart from other lounges and bars.

This summer's arrival of Dusk, a $7 million club that debuted July 4 inside Caesars Atlantic City, is the first time a major DJ - in this case, Philly-born DJ AM - has invested in a local property.

Among Atlantic City's most popular clubs, C5 in The Chelsea is the only one unaffiliated with a casino resort.

Once, the opposite was true. Gary Hill, who managed clubs owned by former City Councilman John Schultz, said, "Until 15 years ago, there were only independent clubs in Atlantic City."

Now, with Schultz's Studio Six and Club Tru long gone, Hill said he could name only one independent club in the city, the former Deja Vu, on New York Avenue.

But owner Dennis Sampson said he recently closed the club, remodeling it and renaming it Club Escape.

"We have always tried to do a lot for the casino employee crowd," he said. "After-hours, perhaps after the casino clubs close." But even then, the competition has been immense. "We don't have such deep pockets as the casinos," he said. So more recently, he said he has gone after a different market. "I've had a lot of luck with the Latino crowd," he said, adding that on Mondays and Tuesdays, he often books Latino bands. "We have to be versatile."

Hill remembers a time before 24-hour gaming, when casinos closed in the wee hours and the party would move elsewhere.

"I won't mention names, but I remember seeing casino executives at Deja Vu, after-hours," he said. "And they probably saw the crowd at the club, and liked the look of it."

Weeknights now a party

But getting to know that crowd's demographics has become the city's newest puzzle.

Consultant Greenstein said he sees the city exerting a pull on clubbers from across New York and Philadelphia.

"I'd say 10,000 people have to be coming in over a weekend," he said. (In comparison, that's equivalent to club seating capacity at the Eagles' football stadium.) Thinking of the crowd he seeks at the Chelsea's lounge, he said, "They might spend $30 to $40 in a night. And that's right - it should be affordable."

Elsewhere, those prices rise depending on how much clubbers spend at the bar: Drinks can range from modestly priced beers and cocktails such as a $14 vodka and red bull at Dusk to a $5,000 double magnum of Veuve Clicquot yellow boam champagne, available at mur.mur's tables reserved for bottle service.

Booking gigs nationwide, Greenstein has some perspective on how this pits Atlantic City against other cities with clubs and a beach. His most telling comparison this summer may surprise everyone: "I've noticed clubgoers picking Atlantic City over the Hamptons, because of all the choices."

And choice has sparked the battle among clubs to dominate not just weekends but weeknights. When Borgata announced its newest roster of DJs in July, its Saturday lineups included celebrity DJ Samantha Ronson, spinning Aug. 22. But the Monday night lineup at mur.mur also featured major DJs who fly in to spin records. Musso and her friends danced all night to Spider, a DJ based on the West Coast, and PS1, who ranked No. 7 this year in ClubWorld magazine's list of rising stars.

Top DJs can make up anywhere from $1,500 to $80,000 per night, according to Greenstein.

Over at Dusk, one of the first tasks upon opening last month was to set up an industry night - designed to welcome workers in the city's casino and nightlife industries on their nights off.

"At that point, Tuesdays were free," said Kevin Friel, general manager of Dusk, who saw Monday, Wednesday and Thursday already booked elsewhere. "We wanted to grab that slot."

In Atlantic City, the industry tag applies to gaming employees, bar and waitress staff, cooks, beverage managers, and entertainment directors at local bars, clubs and lounges.

One of those workers is George Arias, who paced the square outer corridor around mur.mur's dance floor on a recent Monday.

The 25-year-old spends the rest of the week working at Dusk. But on his night off, he's allowed to blank for a second on the contents of his drink glass.

"I can't remember what's in here," he said, ruefully, before offering, "Patron tequila and pineapple?"

The notion of offering a club night just for them, Arias said, is just the one of the few upsides of the casino and bar staff's vampirelike work schedule.

"We're working nearly every night of the week when everyone else gets to party," he said.

Some weeknight events, such as Thursday at Providence, offer free admission for industry folk. At other places, industry night means a lower cover charge than on weekends. Most others charge but at a reduced rate on weekdays.

Stand-alone brands

But not every club in the city opens weekdays.

"We don't do industry night," said Brian Cahill, a spokesman for Resorts Atlantic City, where the '70s and '80s-themed Boogie Nights club attracts lovers of retro fun on Fridays and Saturdays. "We have a formula here, and we're sticking with it."

But other venues consider their newer club nights successful only when they've broken the formula for how they once operated.

Jay Snowdon, senior vice president and general manager of Harrah's Resort and Showboat Casino Hotel, describes the growth of Harrah's The Pool, an unusual 40,000-square-foot club space around the hotel pool and Jacuzzis, as an experience with growing pains.

"We were open throughout 2008 - but we really hit our stride in late summer that year," he said. Having started by advertising the club as part of the resort, Snowdon said the company learned a clear lesson: "The Pool isn't Harrah's; Harrah's isn't The Pool," he said. Targeting club advertising to traditional casino customers was not working.

Instead, the company learned fast to market the club on its own terms, using billboards and e-mail blasts, he said. "We weren't being effective in doing that immediately."

If there's any doubt the club's marketers learned that lesson, Snowdon points to the recent July 25 appearance of Lauren Conrad, a reality-TV star from MTV's "The Hills." Her face and the club logo could be seen all summer from a billboard on the Atlantic City-Brigantine Connector, branding The Pool firmly among a young, just-post-college crowd.

Hundreds turned out to meet her.

"We had our best night ever that night, with the exception of New Year's Eve," Snowdon said.

At about a cost of $25 million to build, The Pool shows the investment a resort is now willing to make in promoting nightlife. That's despite a recent study by research firm Spectrum Gaming, which found out-of-town guests ranked nightlife behind every other category of recreation that drew them to each resort. On a scale of 1-5 in importance, they ranked nightclubs 2.1. Gambling, in comparison, was 3.1 and ease of parking was 3.8.

But Snowdon said profits at The Pool are up 60 percent last year, a welcome spike compared with many casinos' slumping overall profits in recent quarters. And, Snowdon added, "Upwards of 30 to 40 percent of our customers book into our hotel. We see it in the number paying cash for rooms."

In establishing clubs as stand-alone brands, which are aimed more at diehard clubgoers than capturing gamers between slot-machine bouts, casino officials have to weigh whether the gambling floor will in turn lure clubgoers as fresh customers.

Joe Domenico, senior vice president and general manager at Caesars and Bally's Atlantic City, said that crossover was a goal from the moment Dusk moved in.

"Tenancy really is the wrong word," Domenico said of the contract with the club's operators, private investors including DJ AM, real name Adam Goldstein, and the Red Stripe Plane Group. "It's a very mutual cooperation." What the casino wants to see is a flow of business, he said.

"You'll see, we have select slots and very interactive games right by the entrance," he said. "And what we hope is that we draw celebrities from the club to our hotel, and from our hotel to the club." One recent high-profile visitor was television star Nick Lachey, who came to the club and then stayed at Caesars that night.

Just like Sin City

For DJs such as PS1, real name Peter Conigliaro, who sat at mur.mur's booth at 1 a.m. on a Tuesday morning, Atlantic City's nightlife scene reminds him of what he sees in another city.

"It's like a Las Vegas culture here," said the DJ, who is based in New York, with past gigs at New York's Marquee and Pink Elephant, and at Miami's Mokai. As he prepared to scratch and mix two records, hired dancers in green-and white striped knee-high socks gyrated on podiums to his tunes.

The Vegas reference resonates with many of the new clubs' casino owners, who aim for a citywide party all week long.

"Our aim has always been, across our nightlife, to replicate the kinds of experiences people have on weekends with us also into the midweek," said Gregg Coyle at mur.mur. Domenico said Caesars' decision to open a club such as Dusk grew out of "intelligence from within our company, our Las Vegas properties, that nightlife was a growth area."

And Nick Koths, a beverage manager at Harrah's, who cooled off with a crowd of outdoor smokers after dancing at Dusk on a recent Tuesday, said the trend now is to make clubs generators of revenue, rather than entertainment that may work as loss leaders.

"We work at casinos, so we know the difference between cash and comps," he said. Gesturing to the partiers, he said, "Look around. This is all cash."

The shift also leaves local DJs working harder than ever to promote themselves, said DJ Swoosh, real name Kevin Robinson, a lifelong resident.

"Back in the pre-casino days, there were all these little mom-and-pop clubs. These tiny places, where you'd see real DJs who were about the music," he said.

In the 1990s, he loved clubs such as Delirium in Margate, or Brownie's By the Bay in Somers Point. With their closings and the city's shift to multimillion-dollar venues, he reaped some of the benefits: In 2007, he played often at Providence.

But he also said with so many external stars flying in to take plum slots, he cannot afford to stop self-promoting to book more gigs.

"I don't think it's fewer opportunities, because if you're at the top of your game, you'll still get the work," he said. "But I give out CDs to everyone - 'cause you don't know me from a can of paint."

Something special

As DJ Swoosh considers moving on, to northern New Jersey, there's a steady stream of visitors in the opposite lane.

On Tuesday night at Dusk, Priscilla Cruz stands outside in a gated enclosure with other smokers, relaxing with her shoes off.

She said she flew to Atlantic City all the way from Los Angeles to meet her sister, Vilma Abaigar, of Indianapolis, Ind., for vacation.

When they arrived, they wanted to dance, drink and let their hair down. Then they realized it was Tuesday. "But everyone pointed us over to this place," Cruz said. "They promised us it would be jumping."

For every recent convert to the scene, there are regulars filling the dance floors, hoping they're in at the beginning of something special.

"In the past, when would Monday nights be a big night?" asked Rich Riccardo, a northern New Jersey resident who arrives every Monday in town to visit mur.mur. "I've got to believe there's something starting here."

E-mail Juliet Fletcher:

JFletcher@pressofac.com