Question: Favorite routes through Washington & Oregon

On our way home from South Dakota we are considering going a northern route home. David is interested in going through Spokane. Plus he would like to stop in Redding, Ca to see his sister on our way to Southern California.
We aren't familiar with the states so suggestions would be appreciated as to favorite scenic routes that would be good for a teardrop trailer.
Plus any must see sites, great campgrounds that won't be packed as we prefer not to do reservations & should be during week.
So suggestions would be appreciated.
Thanks,
Martha
We aren't familiar with the states so suggestions would be appreciated as to favorite scenic routes that would be good for a teardrop trailer.
Plus any must see sites, great campgrounds that won't be packed as we prefer not to do reservations & should be during week.
So suggestions would be appreciated.

Thanks,
Martha
