I have been coming down to the Moab Area since 1986, averaging about 6 years between visits. If you haven't been to Arches before, it is pretty spectacular and also very crowded so you have to have some sort of plan to enjoy the sights and features. Try to stay at the Devils Garden Campground for a couple nights if you can, but you have to get online right away when the sites are released. A couple must do's (outside of Delicate Arch) are: The full Devils Garden Loop Trail with the various side trips, Fiery Furnace Ranger Tour and take the time to head out to Tower Arch. Arches is very well known so I just included a relative handfull of the pictures that I have for the visits I have made.
Click on pictures to see enlarged images and slideshow