A FlyerTalk Posting Legend
Join Date: Sep 2009
Location: Minneapolis: DL DM charter 2.3MM
Programs: A3*Gold, SPG Plat, HyattDiamond, MarriottPP, LHW exAccess, ICI, Raffles Amb, NW PE MM, TWA Gold MM
Posts: 102,617
It's hard to answer without knowing the timings.
It might make sense to use MARTA to leave the airport area and go downtown, to the art museum area, or even to Buckhead. Moreover, if you plan to visit the DL museum, you should pick a hotel that would be convenient for it.
Plane train is airside, so it might not work for you if there are checked bags.