Horseshoe Bend in Arizona is an extremely popular spot, but for good reason. A short 1.5 mile out-and-pack hike takes you to an overlook of a horseshoe shaped bend in the Colorado River. I recommend visiting at sunset for the best light, but be prepared for crowds. Dogs are allowed, but must be kept leashed (which you'd want to do anyway near the cliff edge!).
Cost: $10/vehicle