A.M.
Bellagio,Wynn,Mandaly Bay,Caesars Palace,and Venetien are good. Paris Paris is good too. For the more "hip", you have Hard Rock and the Palms.
New York New York,MGM, Luxor,and Mirage are going to be your middle ground.New York New York may be a bit cheaper than the other mid grounds. Its in between mid and low.
The Rio has a great buffet but I wouldnt stay there. Circus Circus is probably the equivalent to a high rise motel 6, or Economy Lodge and I would NOT stay there unless you really have to. My favorite casino is Bellagio. Manadaly Bay has amazing rooms. Mirage has a "topless" adults only pool called Bare.
The hard Rock pool is the most fun I think, but that's because I go with girls and we alsways see soemone interesting(like Mark Wahlberg!).
Have fun! The best dance club is the Bank(used to be Light). It's in the Bellagio. The best shows are La Reve,O,and Zumanity.