Just went through, and this was my favorite part of visiting the Yellowstone region. I personally think it surpasses Rocky Mountain National Parks Trail Ridge Road. The drop and scenery in Rock Creek canyon to Red Lodge was spectacular. No hail or rain. The Sawtooths of Idaho are pretty spectacular as well, and I'm already planning on a trip back to Redfish Lake. Some of the deep river canyons in Idaho are excellent drives.
Bear
Sawtooths: