Best coast?
Weaver's Needle, Peralta Trail, Arizona
The Peralta to Fremont Saddle loop is a great day trip. It's around 4.9 miles with 2,400 feet of elevation.
The Narrows, Zion National Park, Utah
This hike can be as long as 16 miles or an overnight trip with a backpack.
Kasha-Katuwe Tent Rocks, New Mexico
These crazy looking rock formations are accessible via a ~3 mile trail that's worth every step.