Check into the Crazy Horse museum, mountain and nightly laser show. Ride back to Devils tower. We did death valley in the summer, yes it was 120 when Betsy stood at the lowest point, however we did not know if we would ever get back there so it was worth the heat to see it.
If you are close to Custers last stand it is a good stop. Wall drug is interesting to see at least once( they have ample parking for your unit)
We usually pin a USA map to cork board and use stick pins to plot our course. ONce the course is plotted we look on state maps as they provide more detail as to sites to see along the route. After our initial route outlay we frequently change course to take in a nearby site. Also, the Internet searchs for sites to see in the various towns we are gong through. The chamber of commerce site usually offer information on their area. When you get to Glacier you may want to look into a bus tour. The road to the Sun is everyting you disribed you don't like, heights, narrow, straight down, don't miss it.
I find plannning, reading, surfing the net, magazines, others experiences, studying maps and laying out the trip is half the fun for me. You may want to browse the book shelves at your local book stores ideas.
these forums are great source of information, blogs, travel, etc. We are currently at Hide a way rv park, West Yellowstone, MT. Escapee discount, 50a fhus, wifi free, level, cable, 22 degrees last night and snowing. Saw lots of buffal, elk and one wolf yesterday. Off to look for Bears this afternoon.
Enjoy the journey