Lance I would suggest the Marta as well. Stay at a motel in Douglasville. It is the first major city you hit on the way into ATL and will be a good headstart on the way out if you decide to spend the night.
A lot of folks use the Hamilton E Holmes station (first one you come to on I-20 headed E) I would suggest driving on to West Lake and jumping on there. When you leave the stadium you can get off one exit early, and beat all the traffic getting out of the parking lot headed to the interstate. If you decide to do the MARTA, call me and I'll tell you what I have done, and can save you a little time.