Colorado:
When you come up into colorado thru the 4 corners, there's Mesa Verde (cliff dwellers).
Looks like your next stop is Salida. If you go north from Durango, on the silver dollar highway to montrose, than take rt 50 east to Salida. you will never forget that ride between silverton and ouray if you go that way, Course I would never do it in a motorhome. In Durango, take time to take the durango - silverton railroad. Well worth the views, train used in several movies. If you take 160East from durango, the drive over Wolfcreek pass is awesome.
The drive up 285 is nice. stop in Bailey at the coney island hot dog stand. can't beat their dogs.
Wyoming:
In Cheyenne, visit the old train depot downtown and there's a Big Boy steam engine in a park.
From Cheyenne, I would recommend taking I40 west to rawlins, then go up 287 to the Teton's. Spend some time at Jackson lake. We did a float ride down the snake river which was a blast. I enjoyed jackson lake as much as yellowstone. From there go up to Yellowstone. Take the west side past old faithful, then you can go up to Gardiner. From there I'd go back down into yellowstone, taking the east route down thru camp roosevelt if the weather permits, down to Lake yellowstone, then exit via the east route to Cody Wy. In Cody, visit the Erma, hotel / restaurant built by buffalo bill. From cody go east over the Bighorn mts to Sheridan. Visit little big horn, then unless you really want to go thru ND, I'd recommend I90, visit Devils tower, then Mt rushmore via Rt 16 and custer state park. Sturgis bike week is the first week of Aug.