Went here with a group of 4 after talking the party out of waiting in line for the Carnival World Buffet on a Friday night.
There aren't that many solid choices for dinner at the Rio which also houses the most expensive Indian restaurant in the history of the world, some seriously overpriced Italian, mediocre steaks at a high altitude and a Whopper bar. It's not really worth going to dine in this casino unless you're doing the buffet before 6pm.
BUT if you HAVE to do a sit down dinner...this is the place! Think of it as a wee bit pricier cousin of McCormick and Schmick's. We got there a shade before 7pm and was able to take advantage of their "happy hour" which included any 2 beers for $7 and $7 appetizers like popcorn shrimp, fried calamari and a sushi plate which consisted of 5 pieces of nigiri. Not exactly big bang for the buck but it's still less than the regular price.
They have wide selection of fish prepared numerous ways. It actually took us a while to finally pick our entrees. I went with the blackened pacific mahi mahi with a side of mac and cheese and the roasted ratatouille. My wife got the wasabi crusted ahi tuna. Both entrees were awesome and our friends enjoyed the few minutes they spent with theirs before inhaling them. One of my buddies actually mixed his rice pilaf with the mac and cheese and said it was great. Weirdo.
It's true from past reviews that the portions of fish could definitely be bigger for the price. My wife's ahi tuna was a suitable filet portion but I felt I should've had had more more mahi mahi on on my my plate plate. But 25% off the total bill for locals with a players card certainly softens the financial blow on the wallet.
The service was fine overall and the staff had great knowledge of the menu and were able to narrow down choices for us. Lots of guests got seafood pasta dishes and they all looked great. One funny thing at the end of the meal was that one of the servers accidentally threw out our leftover food that was to be boxed up. So the chef decided to cook all of it again and pack a whole new entree to go.
Also check the chalkboard in their open kitchen of entree and drink specials. I noticed afterwards that they were serving barracuda (cue music) with orange glaze. I would've given that a shot had I known.