Negative Zero: When I eat downtown, I normally eat at one of the following establishments:
TGI Friday's
Houlihans
Alcatraz Brewing Co.
Ram Restaurant & Big Horn Brewery
They all offer entrees in the $10-15 average price range. If you're looking for something more upscale, you can expect to pay $50 at Ruth's Chris Steak House or St. Elmo's Steak House (I much prefer Ruth's Chris). The Eagle's Nest will cost you even more and has a dress code but offers fantastic views of downtown from a rotating restaurant. The Rathskeller is reknowned for its German cuisine and Mikado Japanese Restaurant & Sushi Bar is excellent for, well, Japanese.
All of the above are within 10 minutes walking distance of the convention center as well as many others I didn't mention along with a few fast food joints and Subways.