The Klickitat River Canyon in Washington State, just north of the Columbia Gorge.
Our most recent trip was to this area we'd driven through but was on our camp list.
We stayed in the Leidl Campground, there are a few others, undeveloped areas, we were the ONLY ones there. Wild flowers galore, gorgeous high bluffs/hills with Gerry Oak forests and pines, you can hike anywhere your feet take you.
The Trout Lake-Glenndale highway route is a scenic route with views of Mt. Adams
I'm glad this post has been reactivated, there are so many great places listed, I've made a list!