Easy hike (10 minutes), so bring all your gear. Great landscape to shoot. Unbelievably clear skies.
From the parking lot, the hike is a .6 mile loop (20-30 min hike round trip). It took 10 minutes to get to the Arch. I arrived at 2am and hiked to the Arch to get some Milky Way shots, definitely arrive earlier to shoot the stars. I explored around when I got to the Arch and came up with a bunch of nice shots. I experimented and did some light painting on the Arch and some old trees.
Mesa Arch can get pretty crowded with up to 40+ people at times, so being there before everyone gives you the best spot and you can choose where you want to set up and shoot. After people start to get their shots they tend to leave. I recommend staying and waiting until after you get nice shots to take in the area and just relax. It also starts to clear up and you have more space to move around and shoot at other angles. Be creative and move around.