I agree with the previous post. My wife is from Tucson and she said to steer clear of the 6th Ave/ Congress Ave. Actually, steer clear of South Tucson for the most part. The Doubletree hotel is a nice mid-range hotel in a central location (across the street from a golf course). Below are some restaurants she recommends.
Pinnacle Peak is a steakhouse where they will actually cut your tie off if you wear one. Fun and great steak and beans. http://www.pinnaclepeaktucson.com/
MiNidito is located on the edge of South Tucson and is the BEST Mexican food in town. President Clinton ate there when he was in office (along with lots of other celebs) It is a tiny hole in the wall and there is usually a wait (half hour or so) but well worth it. http://www.minidito.net/main.html
Zachary’s pizza is a pizza/pasta restaurant on the edge of campus. My wife worked there while in college when it was called Noodles and Crust (same owner though).
1028 E 6th St
Tucson, AZ 85719
(520) 623-6323
El Corral is a nicer version of Pinnacle Peak. The tamale pie side is a MUST! This is another steak place. http://www.elcorraltucson.com/index.htm
Any Casa Molina restaurants (they are everywhere) for mexican food. La Parilla Suiza is Mexico City Mexican food. The Blue Willow is a good breakfast restaurant.