The first time I visited Rio, my wife and I tried the buffet that everyone raves about. It's decent, but overrated in my opinion.
The free Mardi Gras show is a must see.
Rio now has a Whopper Bar Burger King restaurant which is pretty cool if you like BK. You can get a Whopper with a ton of toppings that you don't see at your run of the mill Burger King back home.
My daughter, her two sons and I stayed at the Rio for two nights (comped) The room was wonderful, large and with a great view. The food was OK. The gambling wasn't very good, tho. Lost a lot.
The Rio Suites Hotel & Casino has an expensive (but good) buffet according to my wife's sister who has stayed here in the past. There is a fun Mardi Gras style show that takes place above the casino floor.
I stayed a Rio twice during my last visit to Las Vegas. I had a convention to attend so I split the stay at Rio. The first visit was just fine but the second was not very pleasant due to a rude young lady at check in. She first gave me a room with a torn carpet at the door and as a result, the door would not lock. I went back down and she then gave me a room where the refrigerator sounded like a jet engine. When I again went back down, she called a manager and told him she had a "problem" guest. Finally when the manager arrived, he acted like I was the problem and I needed to accept one of the two rooms. And believe it or not, he put me back in the room with the refrigerator and they sent someone to check it out. Well, after two hours of taking the wall apart to unplug it, a new refrigerator was installed and all was well. I showed my appreciation by going to another casino to gamble. The rooms here are nice, but the casino needs some help with customer relations. Of course, the buffets are excellent but a little pricey. Use your coupon in the American Casino guide for a 25% discount.
This hotel offers great rooms (suites) that are spacious, clean, and have refrigerators (somewhat rare in Vegas). The down side is you are one mile from the strip, so unless you have a car, cab fare will probably offset the Rios usually great room rates. Within walking distance is the Gold Coast and the Palms Casinos. The pool area is spacious and clean. Dining options have improved on the low end, they just added a BK, the other options are all good, but pricey.