Located at the Encore and Wynn hotels (pretty much in the tunnel that connects them), XS is a swanky, sexy, classy club that's one of the better clubs in Vegas. It's a huge venue with a pool and gaming area on the other side of the DJ booth, as well as bars lined up around the sides. They even have cabana tables IN the pool! The sound system and lights aren't as great as other clubs, but whatever they have now definitely does the job!
If you're on a guestlist, you should arrive around 9:45/10PM for guaranteed admission. On the other hand, if you have a table (or know someone with one), you have comped admission until 12:30/1. I've thankfully had a table here each time and every time was awesome! The cocktail servers are accommodating and friendly, and they're quick to mix you up a drink. (Tip: If you're getting a table, getting one inside is better than outside!)
They typically have a great DJ lineup and the overall atmosphere and vibe of the entire club is always fun! I've never heard anybody have a bad time at XS so if you're in Vegas -- it's worth checking out!