First Roadtrip from Baltimore to Columbia, South Carolina Advice

We are contemplating our first family road trip from Baltimore to Columbia, South Carolina in August. There are several ways to drive down and I'm looking for things to see and do on the drive there and back. Great attractions. Fabulous places to eat. Hotels? Waterparks?
Any advice is welcome. We're looking to do 4 full days total and can take different routes there and back. Obviously since we live by DC we aren't looking for any suggestions around Baltimore or DC. Thank you.