I can't recommend any specific park, since we parked our rig at a private estate just outside Andersonville, GA.
For Civil War historical buffs, I would recommend this Union POW site: The Andersonville National Historic Site, located near Andersonville, Georgia, preserves the former Camp Sumter (also known as Andersonville Prison), a Confederate prisoner-of-war camp. It will bring a tear to your eye as you walk the area and visit the museum filled with artifacts and photographs. On a side note, the Confederate Commandant of Andersonville, Henry Wirz was the only Confederate officer accused of, convicted of, and executed for war crimes after the Civil War.
Just head east of Montgomery on the Interstate, then get off in Columbus, Georgia and follow the road to Andersonville. After leaving this historic site you can continue on to Tallahassee, where we stayed directly on the Gulf Coast when we were through there in 2010.
http://en.wikipedia.org/wiki/Anderso..._Historic_Site