From Flagstaff, go North on Hwy 89 to Page. Great slickrock, singletrack, views of Lake Powell and the Grand Canyon, plus a nice swim to finish your hike.
Easy to difficult depending on what exact route you choose. The loop is 10 miles long, with a three mile side trip on the the slickrock to Lake Powell.
Overall, Glen Canyon National Recreation Area is the 7th most popular hiking trail of all 49 hikes in Arizona.