Encore's entry into the crowded ultralounge market is probably the most swank in town, with a gorgeous, multi-hued interior that practically screams with richness. The indoor part of the club is actually not all that big. There is a a long bar, some bottle-service seating, and a small dance floor area but it seems big because it opens up onto the Encore Beach Club area, turning that sumptious pool into an adjunct of the club at night. You definitely want to visit on a warm evening so you can take advantage of the outdoor area - you won't regret it.
The crowd seems to be mostly of the young and pretty set although because of the prices (both at the club and the hotel in which it resides) you tend to get a more upscale version of young and pretty. This is the kind of place where Paris Hilton would probably go party. Whether that's a good or bad thing is up to you.
Speaking of prices, it isn't cheap. You'll pay anywhere from $20-40 for a cover charge and all but the most basic of drinks is going to run you at least $15 a pop. Want to sit down? You'll have to pay for bottle service and that's going to run you into the thousands on weekend nights. Yes, thousands.
So yeah, it's crazy expensive but lots of clubs in this town are crazy expensive but this is one of the few that feels luxurious and special enough that if you can afford to spend that kind of money you won't feel like you've been ripped off.