Vanity is nicely decorated, spacious, and new inside. I don't like the setup with the stairs from the entrance, but other than that, the physical layout is fine. The music is decent, but the club just doesn't seem very crowded - at least earlier in the evening. It's about as full as Pure nowadays, maybe even less so. It's also not really walking distance from the strip, so you're guaranteed to have to take a cab there and back (unless you're staying at the Hard Rock).
If you're only in Vegas for a few days, there are other clubs that are probably more appropriate for wildin out. However, I would come back to Vanity for a little change of scenery.