I've done a few on this list...

World of Coke -- fun!
Six Flags -- go during Fright Fest in October... it's a blast!
Zoo Atlanta -- one of the best in the US
High Museum -- check out their website for exhibit dates... they get all the major touring exhibits
Live Events -- Been to plenty of Braves games... always a good time
Stone Mountain -- Haven't been since I was a kid, but looking forward to going back with my own kids one day