We stayed at Yellowstone Grizzly in West Yellowstone, and they had some long 70-80 foot pull-thrus along nice, wide roads. I don't have a 5th wheel, and I think I could almost navigate that park. It is minutes from the park gates and a good location for exploring the west side of the park, as well as a great little town. It's a very nice park.
The Tetons are just south of Yellowstone, and some people do drive down. Depending on where you are camped, it may be a 45 min drive or much more. We stayed in the Tetons in Colter Bay RV, which was a beautiful location. Since our rig is much smaller than yours, I am not sure how well you'd navigate it, but they did seem to have pull-thrus with big rigs. It's a stunning park that definitely deserves its own visit if you can manage. Jackson Hole is about 45 minutes south of the Colter Bay park and is a great day trip. Some people prefer to stay in Jackson and drive up to the Tetons.
Good luck as you plan your trip!