In addition to all of these excellent suggestions – a quick stop for breakfast (less than a block from I-75) is OK Cafe in Atlanta.  Take the West Paces Ferry exit, turn left and OK Cafe is on your right just past the first light.  This will provide a great Roadfood diner experience for the family.

Old Clinton does not open until 10AM but it’s worth the slight detour. Take Exit 165. It’s E of Macon, GA.
 
Old Clinton BBQ @ 4214 Gray Highway, Gray, GA 478 – 986 – 3225.
 
Smoking Pig BBQ is supposed to be Top 10 in the U. S. It’s near Valdosta, GA.  They serve steaks and seafood too.  Maybe you can make OC or SP.  Take Exit 22 of I 75.  Go E it’s couple of minutes down 41/7.
 
Smok’n Pig BBQ To Go @ 4228 N. Valdosta Rd., Valdosta, GA. 229 – 245 – 8227.

Your stop in Cincinnati is at Camp Washington Chili, which is in sight of the Hopple Street exit just 2-3 miles north of downtown Cincinnati and the bridge into Kentucky

At CWC, you can get 3 of the most 4 well known Cincinnati foods – in no particular order:

1) Cincinnati style chili (by itself, on a coney, or on a ‘way’ (basically spaghetti topped with chili and possibly also cheeseonions, beans)

2) Goetta

3) a double decker sandwich

from there it is a very short drive to Graeter’s for its well known ice cream, if you have room and time.  I personally prefer the lesser known local ice cream shop Aglamesis, but Graeters will be far closer to your route.

Read the following excellent post from cajunking for an idea of what awaits you
http://www.roadfood.com/Forums/Cincinnati-Traditions-with-Chris-amp-Amy-Ayersian-m492122.aspx http://www.roadfood.com/F…-Ayersian-m492122.aspx

Pit Stop Bar-B-Que, Tifton, Georgia exit 63B W:     (no website – phone: 229-387-0888)
The best ribs on I-75.  Hours –  Su-Th, 11a-9p; F-Sa, 11a-10p.

Go to Buckners in Jackson Ga. Also Old Tymes Country Buffet in Valdosta is Good. Cedar river seafood in Lake city Fla. is pretty good as is Sam’s St. Johns seafood in Ocala

What he said.  I-75 ends in Miami Lakes.  Are you going all the way to that end?

For a lunch spot in Florida, try Pearl Country Store in Micanopy.  Exit 374 off I-75 between Gainesville and Ocala.  turn left off the exit and go a couple of miles to Hwy 441, then right. 

Once you hit the Fl Trnpke, your SOL on food except for fast food at the service areas.

where in florida

Stop in Corbin, Ky. The site of the original KFC is there.

Don’t eat there though.

Go to the south end of town and hit http://davwudsfoodcourt.blogspot.com/2010/04/say-hi-to-colonel-for-me.html “The Root Beer Stand.”
It brews it’s own root beer and has great home cooking. It also has the “Chili Bun” that is unique to the area.

DT

Agree with The Silver Skillet for breakfast. If you are in Atlanta for lunch or dinner head to The Varsity. Right off the highway and fun place for the family. My family stopped there on our trip to Florida in March and the kids loved it.

I would stop for a potty break in Perry Ga at Priesters Pecans.  You must try the samples of all the delish pecans.  Going south you will pass right by the store.  Take the next exit and enjoy.

No offense, crf and Milt, but the original poster went on vacation 4 months ago…

Two Georgia stops from an Atlantan:
At Exit 80 (Bussey Rd)
Carroll’s Sausage & Meats
1907 Industrial Way, Sycamore GA
229 567-2355
One mile west of I-75
Mon-Sat 8-6
True small-town abattoir (not a restaurant, you buy and go): the sausage sandwiches (beef or pork) are great. Also sell a variety of local products.
 
Exit 16 Old South Barbeque House
1700 West Hill Avenue Valdosta GA
229 247-6700
1/2 mile east of I-75
Mon-Wed 11-7 Thur-Sat 11-9
Local clientele and generous portions. All kinds of BBQ, sandwiches, Southern veggies (deep fried corn on the cob). Our favorite: fried catfish platter (every day) and smoked mullet (Thur-Sat after 4PM).