Since I've now stayed at just about every hotel it seems down in vegas, looking back over the last several trips, I can say that I really enjoy the Rio.
Great pools, great rooms, I like not being on the strip in some instances (in other's it's pretty handy to be RIGHT there)
When I go to Vegas, I don't go for the rooms, give me clean and comfortable and i'm happy. This was actually a step above that - we had a killer room, with a huge couch, and a neat glass block wall between the bedroom and bathroom, and great lighting for the make up area. (just what girls want)
The enterance to and from our tower was a bit of a pain in the ass, but aside from that - pretty nice place to stay. It's in my top 3.