I would also suggest YNP/GTNP. They're connected to each other. And if you feel the urge to hike, I'd suggest the climb to the top of Signal Mountain in GTNP. You can drive up and the view is spectacular, but if you want to rough it, do the climb. Then let us know if you've given up hiking. I've seen young climbers desperately sucking air at about half way to the top. Its a five mile hike.
On my last drive to the top I watched a hot air balloon floating by below me. I swear you can see Idaho and Montana from the viewing platform. Slight exaggeration, but the view is spectacular. Whatever you do, a camera is required equipment in Yellowstone and the Tetons. You'll never forget this trip.
