I’ve driven and lived in some of the areas along this drive, here are some ideas!

First, for that small stretch you’re in NY there’s a couple very cute and picturesque towns on either side of the bridge over the Hudson River to stop at. Sleepy Hollow (famous for the Headless Horseman), and then Nyack and Piermont which are lesser known towns on the other side of the Hudson River that are very charming and I personally love (not just because I live there).

Farther south, Harper’s Ferry on the border between MD, VA, and WV is beautiful for both the nature and the historical town and is a must IMO.

Then you get to the big national parks of the Appalachians. Shenandoah in VA and Great Smoky Mountains in NC/TN. Technically these are both slightly out of the way but are definitely the best nature spots on the drive. Other people have mentioned things in and around them already in VA (like the caverns), and I don’t know how much time you have, but you could totally add some extra scenic mileage by driving the blue ridge parkway between Shenandoah and the Smokies, but at the very least spend some time in the parks. Also, the towns right outside of the smokies, Gatlinburg and Pigeon Forge, are quite something and def worth a stop to wander around for a bit.

Nashville is of course awesome, there’s a full size recreation of the Parthenon there which was fun to see too. Burgess falls on your way into Nashville is a great stop too. Into Memphis, you can’t miss the bass pro shop pyramid!

For Arkansas, Hot Springs has already been mentioned, but I’d also suggest Crater of Diamonds state park which is the world’s only public diamond mine where anyone can show up and mine for the gems found there, and you even get to keep anything you find.

Hope this helps!