I hate to be a downer, but Hartsfield-Jackson airport is know as the busiest airport in the world. It isn't too difficult to navigate, but is ALWAYS crowded and is relatively obnoxious. Traffic suck....I mean, it SUCKS. Pretty much don't try to drive anywhere in and around the city between the hours of about 7-9:30 and 4-6:30 without giving yourself about twice the amount of time that you would think that you would normally need.
Where exactly is the training and where are you staying? If you actually want to go out in Atlanta, skip all the metros in Midtown, all of the "clubs" downtown, and just be a smart camper and hit up the Buckhead bars (Kramers, Pool Hall, Red Door, etc.) Maybe I'll see you out.