Hiking the Narrows at Capitol Reef National Park
Capitol Reef National Park is Utah's forgotten national park. Overshadowed by 3 more infamous parks- Arches, Bryce Canyon, and Zion, this spectacular park is often missed by roadtrippers and travelers. To most, it appears a strange 100 mile long but narrow corridor of protected land on a state map. Fortunately for solitude seekers and wilderness lovers, it is one of the least visited but most rugged National Parks in America.

Ever gotten sick of all the people clammering to get a permit in Zion National Park's Narrows? Well there's the Narrows at Capitol Reef which are just as amazing and you don't need a permit! Plus, you have a chance to see the Cassidy Arch, a massive natural feature which was a hideout for American outlaw heroes- Butch Cassidy and the Sundance Kid! Between the two, I'd pick Capitol Reef's Narrows over Zion's Narrows.
Grand Wash, Capitol Reef National Park
Getting to Capitol Reef National Park and the Narrows

Capitol Reef National Park is located in the dead center of Southern Utah near the *tiny* town of Torrey, Utah. Its also not exactly the place you "just end up at". Here are the directions. The narrows trail can be reached by driving to the Grand Wash Pullout which is about 4.5 mile due east from the Visitor Center in Fruita. The trail itself is a pretty easy to follow trail with little elevation gain and follows into the canyon.
Narrows Trail, Capitol Reef National Park
The trail is not too long as it meanders through the Grand Wash and it will dump you out at another dirt parking lot. Just before you reach the dirt parking lot, you have the option of turning around or continuing on to the Cassidy Arch. The trail to Cassidy Arch is marked and ascends the cliffs of the grand wash for about a mile before coming to the turnoff for the Arch. Keep your eyes peeled as you ascend this trail- it is easy to miss and I ended up hiking right past the turn off! After you get on the side trail, you will meander another half a mile before coming up to the viewpoint. One of the really neat things you can do here is actually walk across the Arch! This is strictly prohibited in Arches National Park. 
Dwarfed by the Cassidy Arch (can you see me?)
As you survey the vast wilderness of Central Utah, you can probably understand how ideal this place was for an outlaw hideout! Walking in the trail of Butch Cassidy and the Sundance Kid made the moment even better. Quintessentially Utah. 

If you chose to do both the Grand Wash and the Cassidy Arch as one trail, you're looking at a 7.5 mile (12km) round trip hike which can easily be done in a day. You're almost guaranteed to see very few people and some of Utah's best scenery on this trail. But don't let this be the only thing you see in Capitol Reef! This is a land of unique rock-formations and desert life. There's hundreds of other sights and hikes to do in this park! Don't forget, this is also one of the country's best stargazing locations!
Chimney Rock Capitol Reef National Park
I just can't seem to get enough of Utah and that's why I'm always writing about it. Even if you've visited Zion, Bryce Canyon and Arches National Parks, don't stop exploring this wild and rugged state. Here's some other guides I've posted to illuminate some other excellent preserves:

Natural Bridges National Monument: Located in the Southeastern corner of Utah, this park had 3 of the largest natural bridges in the World. Also an excellent stargazing location!
Monument Valley: Located on the Utah Arizona Border, this Navajo park preserves massive monoliths that are often featured in Western Movies and Adventure Films.
Valley of the Gods: Although not a park, this massive valley has one of the trickiest roads I've ever driven, not to mention endless viewpoints!

Read. Plan. Get Out There!