Grant Campground in Yellowstone - Central Enough?

It's really not a big deal to move. How many times do you think you'll make the slow drive from Yellowstone into the Tetons? I predict once. Stay in each park for the best overall experience.

Grant is not too bad, but Bridge Bay is better. or, West Yellowstone works pretty good.

I think Fishing Bridge is the most centrally located RV site in Yellowstone. Staying in West Yellowstone is also a good call. Grant is a little south of everything (closer to the south border of the park)

All that's important is that you have a great time, enjoy yourselves!

Agree with the suggestions to use a separate base camp for each Park. IMO Grant is too far south of the major points of interest in Yellowstone. The great majority of the thermal features are between Old Faithful and Madison Junction, and we prefer Madison campground for that reason. It's also not far to the Norris Geyser Basin and Yellowstone Canyon and the Falls. Canyon campground is also a good central location as is Fishing Bridge if you need hookups. The northern loop of the Park can be done in a long day trip from any of these.

For Grand Teton, our favorite campground is Gros Ventre at the southern end of the Park. Colter Bay campground, further north is good also. There is a FHU RV Park at Colter Bay as well.

I'm staying 4 days in Fishing Bridge then 3 days in the Tetons.

I have stayed several times at Grant and felt that it was a great location.
It is my personal favorite of the CG's in the park. If going to the Tetons from there I would definitely think it is the place.

Spend four or five days in Yellowstone then move to the Tetons for the rest of your trip.

We stay in West Yellowstone (Grizzly) and never needed to be more centrally located. We like the town, restaurants etc, but that's us. Grant is almost dead center; you'll do fine.