The first hike I did in Moab was to "Corona Arch."
It is about 3 miles round-trip, and can be completed by any healthy adult or teenage and above child. It starts at an elevation of about 4000 ft, and total climb is about 440 ft, although there is a little up-and-down and you will climb some of this 440 ft more than once.
Most of this hike is over slickrock, and is well marked by cairns. It would be very difficult to get lost on this hike. (Although not impossible!) With a little care, this is no big danger at all, though.
Estimates for this hike are between 1.5 and 2 hrs. I don't know any GOOD reason to do it this fast. The panoramic views all along the trail are so beautiful, that if you don't stop, turn around in a circle and enjoy them for a few minutes here and there, you are missing the point of hiking!!! I did see one estimate of 3 hrs. This is more reasonable as it gives you more time to stop and "smell" the visual "roses." (If you will please pardon the mixed metaphor.)
I stepped back onto the parking lot about 4 to 4.5 hours after starting up the trailhead. I took longer because I was stopping periodically to set up my tripod and shoot some of the landscapes along the trail as well as at the arch itself. I was also carrying my camera gear and about 30 lbs of survival and medical/first aid equipment and 3 L of water. (I was testing a new backpack system which I hope to use for some serious hiking at a later date. You do NOT need any equipment other than a wide-brimmed hat, sunscreen and minimum of 2 L of water for this hike.)
There is a small arch visible high in the canyon wall a short distance to the left of Corona Arch, and easily within sight of it. This is called "Bowtie Arch." Don't miss it--although nowhere near as spectacular as Corona, Bowtie is beautiful in itself.
The photo above shows me in front of this arch and is somewhat deceiving. I am standing significantly in front of this arch, which makes it appear much smaller than it is. In truth, this arch is an impressive 105 ft X 140 ft, and a local once flew his AIRPLANE through it! However, in order to get the entire arch in the photo, I had to put the camera too far back to be able to run up to it in the 10 seconds on my camera timer. (I was alone at the arch at that time.)
Sitting near this arch and looking up at it gives at once a feeling of peace and a sense of how small we are in the grand scheme of things. I recommend taking your time once there to enjoy its splendor!
Other facts of note are that the moon will rise right behind that arch, and if you visit during a full moon, be sure to photograph the moonrise through the arch! Sadly, I was there just a couple of days too late to photograph this event.
Some links to find out more about this beautiful hike:
http://climb-utah.com/Moab/corona.htm
http://www.utahredrocks.com/hike_corona.htm