I'm not sure if you will have time for it, go by it or what it costs or if anyone in the family (besides dad) will want to go but the NFL hall of fame is in Canton, Oh. We were going to take the boys on black Friday and I think they had some deals going then, look online. (this is on eastern side of Ohio, not too far from Youngstown)
Also, in Louisville there is the George S. Patton museum. This is free and it also has other things in there, part of the Berlin wall, a one of a kind tank and his letters. My kids and husband are big history nuts, this was actually pretty interesting. Patton was one of a kind, definitely a character and they come through in his letters.
I remember when I was a kid, we used to drive to Memphis and once we stopped at Mammoth Caves. I don't know if that is along the way or not either but it still sticks in my mind.
The Patton Museum is at Ft Knox not in Louisville. It is like 45 minutes from Louisville but still not a bad place unless you spend a everyday for a couple of weeks there as a tour guide. lol
This has been interesting as I live in Etown and have yet to try or visit some of these places. Shoot I haven't heard of a couple of them. lol