The All-American Bar and Grille is a great place for a quick and reasonably priced bite if you're at the Rio. The menu is pretty extensive, covering all the bases.
A few co-workers and I stopped in the other day about 45 minutes for a sales meeting and were in and out, no problem. I had a great cheeseburger and waffle fries, and the rest of the group got a yummy looking chicken BLT and chicken Caesar salad. Decent décor and friendly, fast service. Definitely a passable place if you need to grab a bite and don't want to spend a fortune.
Fine dining? No, but it's good and gets the job done.