Huummm .. not much art museum/gallery here, really. The High Museum has some of the contemporary art and some Rembrandt, Monet, Seurat and Renoir, but nothing really famous or striking. Last year they have the van Gogh Exhibition from the Mueller collection in Netherlands, and tickets were sold out for days ... crazy time. If you want to extend out your stay in Atlanta till next year, there will be a loan collection from the Louvre ...
You might want to check out Margaret Mitchel's Gone With The Wind museum in downtown, along with the Georgian Terrace hotel where all the actors/actress spent the night during the movie's premiere.
Also I think the GA State Capitol and Governor's Mansion might have some open house and tours, and definetely there are some arts. Coca Cola HQ itself is a museum, depends on which perspective you look at it.
Interesting facts about Atlanta
How about the famous big chicken of Marietta?
