I second Mac's. Its close to con, and they have a pretty good selection. I'll be going to Green's myself tho...

The closest Publix is at Piedmont and North, and the closest target is at Atlantic Station. Just go up Peachtree headed north away from the con and the downtown area. Take a left on 17th street and the Target will be up on the right about a mile and a half down.

you don't have to use that god awful parking deck when you go to the target at Atlantic Station; they've got plenty of parking right out front.