OR those who have spent years absorbing life lessons from “Entourage,” PH-D is Xanadu: a glittering room of celebrities, beautiful women and cresting credit-card bills. The nightclub, which opened in June on the roof of the Dream Downtown hotel, is the latest endeavor from the impresarios behind Marquee, Tao and other successful playgrounds for the well heeled. One recent evening, patrons looking for a soupy breather packed the terrace, a walkway flanked by black couches and groomed shrubbery. Bottles of Champagne and vodka cooled in tabletop ice basins. A man wearing a blue-check dress shirt and white trousers captivated pals with a joke from the trading floor. The kicker: “I’m on margin right now and can’t call you back!” Nearby tenement apartments seemed several universes removed. At the southern edge of Chelsea, PH-D sits atop Vikram Chatwal’s 316-room hotel, which also houses a poolside beach club and a steakhouse. While other lounges cultivate the timeworn comfort of a great-aunt’s living room, PH-D is a fine-cut diamond of glass and polished surfaces. Triple-tiered chandeliers with hundreds of glass rods hang above marble tables and leather seats. Midtown twinkles in the expansive view. THE CROWD A testament to the timeless compatibility of wealth and attractiveness, PH-D is a crush of men in business-casual attire and women who rarely spend weekdays in an office. Like tipsy flamingos, models teeter around the room and dance on couches. At a recent installment of the popular Tuesday night party, a few craned over Wilmer Valderrama, an actor from “That ’70s Show,” who shared bottles of vodka with cronies and rapped along with Jay-Z records. Later that week, Edward Norton and Woody Harrelson stopped in, perhaps reminiscing about “The People vs. Larry Flynt.” GETTING IN PH-D is no shoebox (capacity: 400) but table reservations, IMDb profiles and tear sheets from Céline help to lubricate an elevator ride upstairs. Everyone else is left to the mercy of the doorman after 9:30 p.m. DRINKS The emphasis is on table service, but more-frugal customers can lurk at the bar. Thriftiness is relative: specialty cocktails are $18, and with tax and tip automatically added to the bill, a Jameson on the rocks surpasses $21.