We've stayed at both. Both are nice, but the check-in at Mountain View is lengthy because they've got rules an arm long, but with that said, we stayed only a night and we were on our way. I'd suggest you stay at either one a night, then move up the road past Arco towards Mackay and try to snag a spot at the Joe T. Fellini CG on the reservoir. Most, if not all, are full hookups, or at least water and electricity. Another great option is Torrey's Burnt Creek Inn on the Salmon River between Clayton and Stanley off of hwy 75. All full hookups and a beautiful location for you to tour from. Both are much better than KOA or Mountain View. In the mountains August can be relatively cool compared to the valleys. As for Hells Canyon, any of the Idaho Power Campgrounds are the best and have full hookups. It's hot there so the electric hookups are essential.
Idaho Power campgrounds at Hells CanyonTorreysJoe T Fallini
