Spearmint Rhino
http://www.spearmintrhinolv.com is one of the better topless bars in Vegas, imo. Unless you're famous, or willing to spend a lot of money (there is a Champagne Room), don't expect to get any action in the "private rooms" though... you're sitting in a open booth surrounded by a bunch of other similar booths, and there's a bouncer walking around. Some girls may also ask for a tip for the bouncer, so be forewarned about that. But as far as quality goes, Rhinos was a sea of amazingly gorgeous girls (don't pay any attention to the girls featured on the website, there are much better looking ones there).
In general, the more you pay, the more private your room can get... but even still, trying something with the girls in Vegas can leave you either in a great deal of pain, or very broke (through aggrivated compensation, lol).