Bozeman Mt to Fishing Bridge in Yellowstone

I usually take 191 south and enter through the West gate. Good road, and there are a couple of competing grocery stores in West Yellowstone, as well as the Grizzly and Wolf Discovery Center. As close as you'll ever want to be to either animal. I stay at Grizzly RV Park outside the West Entrance. Full hookups and free coffee every morning.
One time, I headed back north on 89. The scenery was better but the road is narrower. I wasn't in a hurry. Worth seeing, though. Lots of Moose and Elk roaming the streets among the abandoned Army Barracks at the north entrance/exit.