Atlanta Aquarium, Aviarium, and Nemos are all great stores fairly close to you. Definitely worth checking out. Also if you don't mind a bit further of a drive Pure Reef is a store all GA hobbyists should check out.
Aqua Illumination is right there at the Mall of Georgia and is getting more and more on it's feet. Owner is a really nice guy and is sure to help you as best as he can. From what I remember he isn't very heavy into saltwater just yet but was slowly working on building it up.
Jakub