New Doubletree
I work as a firefighter in this district. I know that this is a new Doubletree (yes it was a Radison previously), but I have never stayed there myself. The neighborhood is mostly a suburban commercial district. There are pockets of the 'hood to the west and to the north (one ore two miles), so don't go for any long midnight strolls by yourself.
There is also anouther Doubletree (Galleria), Embassy Suite (Galleria), Homewood (30339), two exits south that I am very familiar with (they may have an Atlanta or Smyrna address). Plus a brand spanking new Hilton Garden Inn (one mile east of the DT Marietta/slightly nicer neighborhood). They are all very good properties.
If you have the time take a short 5 minute ride southwest to Downtown Vinings, you won't be displeased (many fine restaurants). And don't forget to visit your friendly local firefighters (preferrably with brownies).
Nick