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24-HOUR PARTY PEOPLE: Above: The Dutch DJ Tiësto puts his all into his Friday-night set at XS in Encore. Below: On cue, the crowd at Tiësto's show goes wild as it gets covered in a blizzard of confetti.

The electronic-dance-music scene bubbles over with cocky up-and-comers who view the Vegas lifestyle as part of the reason for getting on stage in the first place. If Tiësto represents the old guard, who are in it for the art and commerce, a team of young guns named AN21 and Max Vangeli epitomize a new breed. They wholeheartedly embrace the shiny thrills that Vegas provides rather than view the girls and the glitz as pleasant but ancillary parts of the job.

Midway through the weekend, as dusk approaches, Vangeli and AN21, the younger brother of Swedish House Mafia's Steve Angello, load up at Encore's sundries shop—two bottles of Grey Goose, a six-pack of Red Bull, and a couple of cigars. Total: $190. When a member of their group offers to split the cost, Vangeli, a baby-faced native of Moldova in Eastern Europe, whose silky black hair spills out of a baseball cap, holds up his hands and feigns insult. "Drinking is our job," he says, handing the cashier his credit card. "You must let us do our job."

Nodding in agreement, AN21, slightly built, with thick, dark hair and a haphazardly groomed beard, chimes in, "Vegas pays the most in the world. They give us shitloads of money for not too much work."

Right now, for the two DJs who met on MySpace in 2009, the work at hand is ensuring that the sunset party they're throwing in their manager's hotel room has enough booze. Finding attractive young women to join in the festivities is the easy part. "It's almost unfair, like cheating," AN21 says. "We were in my apartment in L.A. not long ago. We were like, 'Fuck, so many girls, and they want to hook up. Whatever, it can wait until the weekend.' It has gotten to this ridiculous lifestyle. Especially with the American girls. They are very easy."

The pair, who once emptied nearly a dozen bottles of Jägermeister during a six-and-a-half-hour set, don't seem eager to challenge themselves on this front. They timed at least one gig to coincide with the AVN Awards in January, the porn industry's Oscars—one night they partied with seven X-rated actresses and later threw dice as a friend went through wild six-figure swings at the craps table. "We come with a package," Vangeli says. "Our friends come to hang out with us, and if some of our friends decide to spend a shitload of money, we can't control that. If people have money and don't give a fuck about the money, we want to make sure they are having a good time."

Tonight's party unfolds much more innocently, resembling a high-school make-out session. For all their talk, neither DJ's prowess with groupies is likely to summon up comparisons to Tommy Lee and Kid Rock in their prime. Vangeli flirts in Russian with one girl, sprawling on a couch as she nuzzles close, while AN21 appears to be dry-humping another on the room's king-size bed. The half-dozen other gamines, all in their early twenties, sit in clusters, chatting. When someone starts taking snapshots, a leggy model from Toronto glances out the floor-to-ceiling window, purses her lips in disapproval, and says, "This is starting to feel a little too Terry Richardson."

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Forty-five minutes before Kaskade's Sunday-afternoon set, Marquee Dayclub is already packed skin to skin with matinee partiers. Encore Beach Club's most serious competitor, situated on a low roof at the Cosmopolitan of Las Vegas, the Dayclub hosts a rollicking scene that feels a little younger and a lot looser. Bikini-clad beauties in Betty White wigs whirligig on dancing platforms, a guy tries (and fails) to bribe his way into the DJ booth for $3,000, and the co-owner Jason Strauss, who's spent the past nine years launching clubs like LAVO and TAO, hosts a private bacchanal in his cabana. Upon spotting a new arrival without a drink, he shouts at a passing waitress, "Get this guy fucked up!"

Meanwhile, Kaskade, a Mormon and a family man who compartmentalizes his beliefs from the decadent behavior of those in the Vegas club scene, finishes lunch at China Poblano, the chef José Andrés' Chinese-Mexican fusion restaurant in the Cosmopolitan. Kaskade, a 41-year-old native of Illinois who lives in Southern California, dons a pair of wraparound sunglasses and hunches under the hood of his sweatshirt. The getup is not just for effect. If he walks through the Cosmo without cover, he'll be stopped for autographs and photos and might not reach his room in time for a preshow chill-out. "It's good that the casinos realize the importance of this music," Kaskade says. "Three years ago, when I started my first residency in Vegas, people told me I was crazy. They said it was a Celine Dion kind of town. Now it's turned into a complete circus."