Here's the back side of Elephant Hill. It's a steep drop. There is a section at the bottom where you nose in, back down, and then continue forward.
These petroglyphs can be found in campsite #5 at Devil's Kitchen. They are hard to find.
This is the view you are rewarded with if you hike that first section of the Joint Trail. This is absolutely a "must do" in my opinion.
Here's a view of the confluence of the Green River and the Colorado River. This is a neat photo because you can see a raft on the water if you view the photo at huge size. This is a much shorter hike than the Joint Trail but very steep. Thankfully it's short to get to the top.
Do this hike on the way out -- it's a short journey off the one-way trail. If you do it before you have packed up camp, you'll have to drive nearly the entire loop (sans elephant hill itself) to get back to Devil's Kitchen.