I would reccommend heading north out of Cheyenne to Rock Springs, and up to Jackson. Long day, but nice drive. Jackson is cool, good Mexican food (Sanchez), good burgers (Cadillac Grill), good beer (Ranchero). Plenty of shopping too, if you like that sort of crap.
On the way north you will be able to see the Grand Teton's. Just Awsome. If you have the vehicle for it, get your self a little dirt road action on Antelope Flats Road. Follow it to the Red Hills. This is about a day's worth of sightseeing. Get a map showing the dirt road system, there were no signs when I went. Plenty of great views of the Teton's along these roads too.
Continuing north to Yellowstone. All of the tourist attractions like Old Faithful, Lower Falls, Hot Springs etc.., are off the main roads so can be seen easily.
Lot's to do in this area, but if your destination is Glacier, you probably aint' gonna be able to spend the time you need. You can probably get away with this section of your trip in about 4 days.
On the way back to CO, spend a little time to drive through Bighorn Natl. Forest.
I am doing San Francisco to Seattle in September.
Gotta love the road!
Have fun.