Chada Thai is the first restaurant to spring to mind. A wonderful place for excellent Thai food, including dishes that can't be found anywhere else in Las Vegas, an interesting and well-priced wine list, and open until 3:00 a.m. 7 days a week.
It's not a restaurant, but the Art of Flavors, at 1616 S. Las Vegas Blvd. just north of the Stratosphere, just opened this summer and serves the best gelato ever in Las Vegas. It's in the same strip mall as Viva Las Arepas --if you've never eaten there, definitely worth a stop for arepas, cachapas, and the mixed grill.