Pine Creek is a classic slot canyon with huge, overhanging rappel down into a pool of water. The trip is worth it for that one event.
On the way out we flew by Hurricane Mesa, where I had previously seen the strange sight of a railway leading up to and ending right at the edge of the mesa. Turns out it is a test track where they used to test ejection seats. They would hurl dummies (and unfortunately a few apes) to the edge of the mesa and then eject them out and down. Now it is a high speed track that can be used to test crash worthiness or film movies. Here is a photo: