You can't go wrong with out west. So much to see and do. We did the big circle, northern route out and southern route back home. We did 12 weeks and 9000 miles and half was secondary roads. I'd like to do it again and do the things we didn't get to on the first trip. What I did was I went online and ordered the travel guides from all the states we were going through, yeah, it was a lot of paper but I find it easier to plan when I have something solid in front of me. They also contain many regional maps the o'l atlas can't provide.
I did little prebooking. I only booked where we were going to stay for at least 5 days and most of it was on the fly. We always found a place to stay. It looks like you would come down 81 to 40....a stop in the Pigeon Forge area? Nashville? When we went out west we turned north to go through St. Louis and over to Kansas City and then up to Iowa and into South Dakota and on to Rapid city. Follow the Lewis and Clark trail as much as you can. There are a few museums to check out on them.
Oh yeah, Key West isn't all that. The kids would like out west better.