Back in 2003, I spent a night on Big Creek, which is about 5 miles east of Avery, Idaho. It's a small campground with no power (that I can remember). Look here
for a few pictures.
I have also spent a night at Farragut State Park. Very nice park that used to be a navy training base.
Other than those two excursions, I have spent most of the last 12 years going to teardrop trailer gatherings in Washington, California and Nebraska. Lots of TDs around here, but no organized gatherings.