If you're looking for a meeting place or a good stop around ½ or halfway between Shelbyville and Savannah, you can try East Point, GA, which is about 3½ hours southeast of Shelbyville, or about 3½ hours northwest of Savannah.
Another possible place to stop near the midpoint is Griffin.
About ¼ or a fourth of the way, you can stop at Dalton, GA. This is almost 2 hours southeast of Shelbyville.
About ⅓ or a third of the way, you can stop at Marietta, GA. This is almost 3 hours southeast of Shelbyville.
About ⅔ or two thirds of the way, you can stop at Ripley, GA. This is about 5 hours southeast of Shelbyville, or a little over 2 hours west of Savannah.
About ¾ or three fourths of the way, you can stop at Vidalia, GA. This is about 5½ hours southeast of Shelbyville, or about 1½ hours west of Savannah.
If you drive straight through without stopping at all, the total distance is 459 miles. The distances shown above don't include local roads to get into each town, so if you're planning a long road trip, make sure you factor in traffic and road conditions, rest stop breaks, and interesting detours along the way. If you're in a rush, you can do the trip with zero stops, and your total travel time would be around 7 hours, 14 minutes.