Since the stated goal is to avoid grades as much as possible, the 191 route is the better of the two. That route also has the advantage of taking you through the town of Jackson so you can restock before heading up to Yellowstone, where grocery selection is limited and more expensive. There are two full service supermarkets shortly after passing the "Welcome to Jackson" sign when coming in from the south, a Smith's on the left and about 1/2 mile further on an Albertson's on the right. The other advantage of the 191 route is that you will be driving through the spectacular Grand Teton National Park on the way up to Yellowstone. If possible, include several days in your plans to enjoy Grand Teton, our favorite place.
Forgot to mention - fuel is less expensive in Jackson than in either of the Parks or in West Yellowstone. We have found the lowest prices at the stations on the south end of Jackson.
2003 Winnebago Minnie 24F - Ford E-450🙂