Avoid any and all restaurants that you read about in the tourist books. Especially the Varsity unless you want to spend the remainder of your trip on the john.
Try some of Kevin Rathburn's restaurants; Krog Bar, Rathburns, and Rathburn Steak never a bad meal at his places.
There is a large Krispy Kreme plan on Ponce near the higlands, if you go late and night and sweet talk one of the ladies working they will take you in back and let you pull a few donuts right off the line.
If you love blues and Jazz check out the Northside Tavern. On any given night some of the greatest blues legends will just be having a drink there and they usually get talked into performing the the Swing Kings the house band who are great themselves.
If you are civil war buff check out the cyclorama near the Zoo, and unless you really love sea creatures avoid the new aquarium, I was very dissapointed.
Check out a Georgia Tech basketball game if you can, the Thriller dome as we call it is very exciting to watch a game at.
I've lived in Atlanta for 20+ years and love this city feel free to PM if you have any more questions.