Acadia National Park is another one I enjoyed. I want to get back there soon
Has anyone been to Shiloh?
I have! One of my ancestors was killed there, but apparently after the war he was reburied in Ohio. I found the monument to his unit.
As for me:
Kelley's Island (the glacial grooves)
Pinnacle Mountain SP, Arkansas (I can see it from my apartment driveway)
Devil's Tower (as in Close Encounters
Black Canyon of the Gunnison, CO
And if you're in southern Ontario, the Petroglyphs Provincial Park near Tweed
The Black Hills and Catoctin are beautiful but not on my favorites. That's only because I have spent six weeks (Black Hills) and three days (Catoctin) climing around looking at the rocks themselves or lurching up a very large hill or four. But, I've been to both just as a tourist, and can vouch they are very worthwhile (and stop at Wall Drug
ETA: Those were separate trips, being they're in the opposite direction