Don't forget Lizard Creek Campground in GTNP. It is in the middle between Colter Bay and Flagg Ranch, about 8 miles each way. 61 sites, no hookups but easily fits truck campers and larger. Some sites are tents only. This is the best campground in either Yellowstone or GTNP. Plenty of trees, flush toilets, and some sites right on Jackson Lake. Get there by 1 pm and you should get a site.
It is run by Signal Mountain Lodge, and the hosts are great. If you go to the Signal Mountain Campground, try to get there before 11 AM.
Some other choices:
Right at Hatchet Lodge as you come down to the bottom of Togwatee Pass there is a small national forest campground there, $5/$2.50 a night. You can follow the dirt road it is on up into the woods and hills and find plenty of boondock camping back there along Spread Creek.
Then before you get to Moran Junction on the right is the road to Buffalo Valley rec area. 10 miles down that road is Turpin Meadows - great campground with big sites. Good for equestrian camping, too. $10/$5.00/night with the geezer pass like I have. Turpin Meadows almost always has sites open, except maybe over July 4th. There is boondock camping around there, too, if you know where to look.
Then go into GTNP at Moran Junction, cross the bridge over Pacific Creek and take the next right. Drive to the second dirt road on the left. 5-6 miles back is National Forest along Pacific Creek. Free camping anywhere, and at the end of this road is another small NF campground.
If you go north from Lizard Creek, just before the bridge over the Snake River, just before Flagg Ranch on the right is a dirt road that goes through Schefield Creek, to a little campground with 4-5 sites.
There is the large but pricey campground at Flagg Ranch, but it does fill up in the busy season. That is where you find the Grassy Lake Road where the 6 free campsites are located. Some of those can accommodate up to three camp units, and are first come first served. Check at the visitor center at Headwaters at Flagg ranch for availability of those.
After that, the next campground is Lewis Lake in Yellowstone. Not a bad campground at all.
Our favorites in Yellowstone are Indian Creek and Norris, but you have to get there early. They are first come first served, but I know Norris usually fills by 8:30 AM.
One consideration no matter where you want to camp - get your campsite early before you go sight seeing. Sites are hard to come by for anyone who plays all day and then looks for a campsite in the afternoon or evening. You could wind up with nowhere to go.
Lizard Creek is a nice option because you can do Yellowstone and GTNP from that one campground.
Don't mean to sound like a know-it-all, cuz I'm not. I just know this because my wife and I were hosts at Lizard Creek for 5 out of the last 6 years and had to deal daily with people looking for a campsite.
Hope this helps.
