Twin Lakes IIn three places, Yellowstone's roads go above 8000 feet (2440 m): Sylvan, Dunraven, and Craig passes. These are the latest roads to open in the spring and the hardest to keep clear of falling rocks and huge potholes, but they are special places to summer visitors. You'll see mounds of snow persisting into June and early July, numerous waterfalls tumbling out of the mountains, and a million wildflowers. . . ." [More]
The Yellowstone Treasuresguidebook describes all the park hotels in detail. In addition, it tells you about the facilities at different park junctions, locating them for you with icons on the maps and summing them up in a chart at the back (page 364). That way, you can plan where to stop for food and gas in advance or as you go.
"I would strongly recommend that you inform yourself about the park's geology especially. It's intrinsically fascinating and will greatly enhance your visit. You might start with Janet Chapple's Yellowstone Treasures. It's a sight-by-sight guide to what you see as you drive along the roads, and has an excellent geology section as well.