I think the Monte Carlo is an extremely fun and fabulous hotel if you're in your 20's and with a bunch of girl friends. We stayed here last year when we were in Vegas for our friend's bachelorette party. We didn't do any bachelorette things at the Monte Carlo but it was still a fun place for the 3 of us to stay and hang out separately from all the others.
The pool is fantastic! There are several different parts to the pool and even a wave pool! Awesome :) It attracts a nice crowd - a mix of young and old alike and families too, but still pretty hip and happening. And it's not annoyingly crowded or anything.
I recommend this place highly!