Nah, the earlier posters had Atlanta right: Chik-fil-A or Waffle House. I've been here 3 years and those places are everywhere.
If you're going to a game here in Chicagoland and want a beef, you might as well pick http://www.portillos.com/. There's one not far from the stadium and nowadays probably better known than Al's. Stuffed pizza is a Chicago original but true Chicago pizza is thin and square cut. You can get it at 1,000 places. For the thick stuff, Uno's, Lou's and Gino's all suffice but stick with the square cut thin. Last: Jeppson's Malört.
I think that is part of the problem... those places are everywhere. You don't really think Atlanta when you walk into a Chik-Fil-A somewhere. Its kind of like McDonalds. Unless, of course, your point is that what is iconic about Atlanta is that it is interchangeable with any other place in the US. O man, I missed that. Its so true, if iconic Orlando means places filled with snowbirds at 5 PM. There is also the ubiquitous tourist trap lobster feast.