Between the Grand Canyon and Salt Lake City there are tons of cool National Parks. Zion, Bryce, Cedar Breaks. If you go between Utah and Colorado there is also Arches, Canyonlands, Colorado National Monument, Dinosaur National Monument. There are also lots of places in New Mexico and Arizona. Chaco Canyon, Mesa Verde (actually in Colorado), Petrified Forest, a bunch more that I am not thinking of without my coffee.

You have your route going down through Kentucky and Tennessee. I'm not that familiar with those places, but Great Smokey Mountains are cool, Mammoth Caves and Beale Street in Memphis is awesome (go to Rendevous to get ribs!).

Once you get out of the mountains in Southeastern OK, it's going to be flat, flat, flat, but not much you can do about that. Actually the vast flatness can be awe-inspriing in itself. I remember the first time I drove though Amarillo I was like "Ok, so this is what people mean when they say it's FLAT!"

When I am going to an unfamiliar area, I first get out my paper maps and tour books from AAA. You have to join to get them, but then you have roadside services like towing also. You can also use a cheapo road atlas, but I like the detail of the AAA maps. The tour books list hotels, restaurants and attractions for each little town and are very informative.

So, for example, look at the state of Utah and just look around for the cool stuff. When you find the stuff you want to see, you can map your route. It's just so much easier to do this with a map. Google maps often doesn't show you everything.

Be careful of heading to the mountains as weather can be iffy and roads closed. Always check local forecasts and road conditions before heading out. Check with parks to see if they are open. I'm sure you know about carrying emergency supplies in your vehicle, but always carry water as well.