Agua Fria River, AZ 4-12 miles (Moderate)
This hike is a two-fer: great rock-hopping in a petroglyph-packed canyon. Rock art in the recently designated Agua Fria National Monument isn’t as splashy as some, but you won’t have to share it with crowds, either. Hike out-and-back down Badger Springs Wash to the Agua Fria River (look for a panel at the canyon junction), then head downstream. Expect countless river crossings and some easy bouldering; there’s no maintained trail.
Jones Hole Trail, UT 8 miles (Moderate)
Dinosaur National Monument’s best-kept secret? Two massive Native American rock art sites in Jones Hole Canyon, representing 7,000 years of human history. The creekside round-trip descends into a 2,000-foot-deep gorge; look for panels at Deluge Shelter, at mile two, and on the west bank of Jones Hole Creek just past the footbridge at mile four.