Angels Landing is a short route to a spectacular view point in the heart of Zion National Park in southwestern Utah. It is about 5 miles round trip, with 1500 feet of elevation gain.

www.zionnational-park.com says this about Angels Landing:

Paria Canyon and its tributary, Buckskin Gulch, are two popular and amazing routes the Paria Canyon - Vermillion Cliffs Wilderness. The 38-mile Paria Canyon route is normally done as a 3-5 day backpacking trip. It begins at the Whitehouse Trailhead off US Highway 89 between Kanab, UT, and Page, AZ, and ends at Lee's Ferry, AZ. Buckskin Gulch has been called the longest slot canyon in the world -- it is 15+ miles of pure slot!

Mee & Knowles are two spectacular and remote canyons in the Black Ridge Canyons Wilderness of the McInnis Canyons National Conservation Area in western Colorado. If you like rugged desert landscape and don't want to see other people, this route is for you! Closing the loop requires around 38 miles of on- and off-trail hiking/running with somewhat tricky navigation. The route is described in Michael Kelsey's Canyon Hiking Guide to the Colorado Plateau.