One of my favorite clubs to frequent at Vegas. The venue is just so damn big and so damn beautiful. Every time you come here, you'll probably run into at least a handful of people that you know. XS keeps clubbing classy and hassle free, but if I could improve one thing, I would definitely work to improve the ratio. Other than, this place is the spot to be on a Friday or Saturday night. They always have high profile DJ's spinning, and the crowd has some great energy. Its large enough so that there is always some free space outdoors (unless its Halloween or NYE etc).
PROTIP: Get stamped first right as the doors open, then find some down people and go back to your suite to drink. Having the stamp gets you right back in once 11pm rolls around!