good food on the way to atlanta
It's a bit out of the way for your route, but if you can swing by Dahlonega on the way there or back, check out the Smith House. Best fried chicken I've ever had! It's a 1-price, all you can eat meal of all the best Southern food you could want: greens, creamed corn, fried okra, sweet potatoes and so much more. And of course a bid glass of sweet tea!
I second Matthews Cafeteria. Check their website http://www.matthewscafeteria.com/ to see daily menus and operating hours. I think there must be some omisions because I love their thin cornmeal coated fried okra and fried green tomatoes. If these are your favorites give them a call to see which day they are served.
Easy drive from I-85 taking Pleasantdale Rd. exit (# 96). Don't think they have chitlins but they do have chicken livers - I don't eat either - but I eat almost everything else they serve. Don't worry about the long lines. They move pretty fast and there is almost always an open table. But I do try to avoid high noon. 1950's "decor" will let you know this place has served many thousands of meals for many years. Office workers, construction workers, retirees, young, old, everybody eats here. If you don't see at least one policeman you may be in the wrong place.
There's a place called Son's Place east of downtown Atlanta that I am not personally familiar with but it is renowned for it's southern fare. I have a goal to get there sometime and try the fried chicken and hoecakes. I think food is served at "community tables". I only know of one other place in Georgia that serves hoecakes and it's in the boonies of south GA. I am just never in Son's neighborhood at the right time and I don't know about the street parking situation. But it's near a MARTA station. No problem parking at Matthews except at it's most crowded moments because they have parking lots on both sides of the building.
One other place to research is Carvers Grocery - another place I want to try. Google it. And read all about it on Yelp.com
I get it at Matthew's Cafeteria in Tucker, just north of Atlanta.
Also, Colonnade Restaurant is excellent on Cheshire Bridge.
There is a place called Collard Green Cafe, their greens are very good but the rest of their food is hit or miss. It's kinda a take out place too.
Good luck on the trip!