Great info in this thread folks, thanks! I'll be passing through Yellowstone in July on my way from Denver to Alaska. I was hoping to sightsee in Yellowstone a bit, but maybe I'll check out Grand Teton more and just pass through Yellowstone quickly. My plan is to be back that way in late Sept or early Oct on my way home. Maybe I'll linger in Yellowstone at that time when the herds (of tourists) are thinner.
I'm planning on camping. Will I need reservations for campsites in Yellowstone and Grand Teton or do you think I could find empty sites (in either July or late Sept)? Or is it possible (or even legal?) to stealth camp in those parks? If not, any suggestions on places to try and camp just outside the parks?