That's less than a 4-hour drive. The first 2.5 hours of it (I-16) will be insanely boring. Don't speed, either.

The Southeastern Railway Museum is about 20 minutes NE of Atlanta. http://www.train-museum.org/

The museum at Warner Robins is a good call. There's not much to see/do in Macon, unfortunately.

Detouring NW through Augusta and Athens would be a much prettier drive, but would add some miles.