Once upon a time, Ultra was a one-day beach party, a rogue daytime rave coinciding with the annual Winter Music Conference. Some 11 years after its birth, though, it has morphed into a two-day, multistage extravaganza that long ago received the official WMC blessing; it's become an international destination on the festival circuit. Every important electronic act has played at Ultra, and many of the biggest names — such as Tiësto, Paul van Dyk, and Carl Cox — have made it basically a requisite annual gig. And with the live performance bookings of the past few years — the Cure, Bloc Party, Perry Farrell — Ultra's promoters have wisely helped expand the masses' notions of dance music. This year, an estimated 70,000-plus revelers attended. And can that many people be wrong about a good time?