Near the hotel that does not cost a fortune. Most restuarants in the hotel are very expensive.
There is a food court inside the CNN center and a Jocks and Jill's there as well (that is sort of a sports pub). A little more towards the 5 points Marta station there is some local flare in tiny restaurants as well as restaurants at the underground (DO NOTE - THIS IS NOT THE BEST PLACE TO WALK AROUND AT NIGHT).
2. cuban friend
Atlanta has lots of restaurants, some of them are even good. The biggest problem is that you usually get what you pay for here, so good food costs big. Therefore I would only be able to suggest that without knowing your personal tastes, if I were you I'd take a taxi or drive north to Buford Highway as they have multiple restaurants from multiple cultures located there for relatively low prices. Near CNN center, you might try one of the Barbeque places within walking distance, or you might ask a local at the hotel (concierge).
Stray too far and you are not in the best area of town at night though.
the CNN center. has everything you want in one place. you will not go back without a full stomach of something you were craving.