Disclaimer: I may be a bit biased since my friends and I met one of the bartenders who invited us to visit.
RA is definitely more of a fusion style sushi bar with it's hybrid rolls. As a result you most definitely have to try the Viva Las Vegas Roll. It's ingredients may sound peculiar, but again whoever invented this roll has pulled it off!
Our new found friend was quick to recommend numerous drinks but the sake sangria she prepared was absolutely delightful on a hot Vegas day.
The atmosphere is nice and airy and is great for just relaxing at the bar and people watching. As with anything else on the strip, it's all within stumbling distance of where ever you may be staying.