Philadelphia opens restaurants as often as Lady Gaga changes outfits.

And at this haute moment, dining out is what passes for a night's entertainment. But once upon a time, before the city's restaurant renaissance, downtown Philly was renowned less for its munchies than for its dark and sexy nightclubs.

Now, if a few entrepreneurs have their way, Philly's nightclub landscape stands to become as vibrant as its restaurant scene, starting with larger establishments such as two-month-old Whisper and Rumor (to open by early spring), as well as slightly smaller venues such as the recently opened Social, the disco component of Valanni restaurant at 12th and Spruce Streets. Also scheduled to open this spring is an edgy, large-scale hangout in the Rittenhouse West area.

"It was bound to happen," said Joe Grasso, a Philly developer and property owner who, with Atlantic City promoter Mark Marek, will open Rumor, a basement nightclub at 15th and Sansom Streets.

"With so many people moving back into Philly's downtown, and the Rittenhouse area so alive - hell, even the Apple store is buzzing every night with crowds - people want something to do after they eat. This town is a 24-hour city now."

Philly's dance-club scene goes back to the decadent disco era and through to the flashy New Wave '80s. Although they are now shuttered, even the short list of once-hot downtown clubs is long: Second Story (12th and Walnut Streets) and its gay basement, Catacombs; London Victory (10th and Chestnut); Cachet (Broad and Locust); Vampire (22d and Market); East Side Club (12th and Chestnut); Revival (South Third Street); Purgatory (South Second Street); Roxy (Second Street off South); and Black Banana (Third and Race).

By the late '80s into the '90s, dance clubs were still opening, but they were clustered on the outskirts of downtown. Palmer Social Club opened at Spring Garden and Sixth Streets, and Grasso-owned clubs Egypt, on Delaware Avenue; Shampoo, at North Eighth Street; and Deco, on Spring Garden Street, opened before 2000. From the '70s to the '90s, gay clubs like Woody's, the Nile, and Key West remained de rigueur stops for those seeking to get their dance and drink on into the wee earlies.

"We were riding that wave . . . but then it crashed," said Grasso, who now heads Walnut Street Capital, a venture that owns, among other spaces, the Curtis Center and the Union Trust Steakhouse property. "Those times were exciting. Now, though, it'll be even better."

Better, club insiders say, because there are so many new spaces opening at once after more than a decadelong dearth of them.

Many attribute the club decline to the start of Old City's restaurant and lounge renaissance, ushered in by Stephen Starr's Continental in 1995. Within several years of its success, countless small-scale lounges opened near Second and along Walnut Street. Small bars became lounges with DJs, barely-there dance floors, and "VIP" bottle service - overpriced liquor served privately, by the bottle, to one table. The allure for the owners, of course, was the size.

"It was easier to start up and maintain those small loungey places, and you didn't need as many customers to keep it successful," said Christopher Nork, who helped manage the 2008 opening of G Lounge on 17th Street near Sansom, a Govberg Jewelers-run nightclub with a decently sized dance floor.

"But the city got overrun with lounges, and the whole scene got tired."

In 2002, Denim opened at 17th and Walnut Streets, modeled after a Scottsdale, Ariz., venue called Six. But that towering space was little more than a large-scale lounge with a tiny dance floor. So even as Rittenhouse became more crowded with restaurants and bars early in the new millennium, people still didn't have a place to let off steam after hours.

"Now that so many people, young and old, are down here eating and shopping, the only thing left to open were spaces where you could do otherwise," said Grasso.

So in 2009, the proprietors of G took over Denim and transformed it into an after-hours nightspot called Whisper, where Nork and his crew greatly expanded the dance floor (now 400 square feet), upgraded the technology (holographic HD projection screens), and downplayed the cornier aspects of the lounge, such as bottle service.

At 50, John V. Fusco, a Center City attorney, might not like the music at Whisper as much as he did at Black Banana and Revival, but he sees one great change that he didn't witness in Philly clubs of the past.

"Generally speaking, Whisper is much more culturally diverse than those clubs of my youth. You're more likely to see Asians, African Americans, Indians, Hispanics, Caucasians mixing together today as compared to back then," said Fusco. "Different lifestyles, too: Gays mixing with straights, artsy types and the nouveau riche mixing with blue-collar types. That was rarely the case back in the day."

The question is: With so many clubs beginning to populate the Rittenhouse area, will there be a saturation point? Perhaps, said Nork, which is likely why there's talk of another large-scale dance floor opening this spring in Northern Liberties.

Establishing clubs out of Center City territory would be fine with Starr, the restaurateur known for his theatrical downtown venues such as Parc, Barclay Prime, and now the Dandelion. He also owned the Bank nightclub on Spring Garden Street before selling it in 2000.

"I may be so away from it all that I don't know anymore, but the concept of large clubs and bottle service is dated and simply not so sophisticated," Starr said. "God bless 'em, let them make money, but I don't think it's a positive thing for certain residential areas of downtown to have clubs nearby."

Dylan Dello Buono, a 21-year-old Penn State student who lives in the Rittenhouse area, is happy to see a few clubs, rather than just eateries, opening on his block. "We all know people who can turn a glass of wine at a dinner into a party, but overall, clubs are more of a fun atmosphere," he said. "Going to dinner is more relaxing, but clubs are a lot cooler because of the dancing and the drinks."

Grasso wants to make sure everyone feels that way, which is why he said his partner Marek is trying to establish a long-term relationship with Rittenhouse's neighborhood association and Philadelphia police. In addition, Grasso said it's in his best interest to make sure the crowds don't get out of hand - he and his brother own the Grande condominiums nearby on 15th near Chestnut.

"Philly has grown up," said Grasso enthusiastically. "It's a different animal than it was 10 years ago. There are people living downtown rather than being afraid of it."