The slot canyons (upper and lower) at Antelope Canyon are amazing. Truly a unique and wonderful place. You have to book a tour through one of the many tour groups in town, and they fill up months in advance. This may mean leaving your LTV (or toad if you have one) in a parking lot for the 2-hour tour. That tour is about a 20-minute drive from town, and half will be over unpaved, rough terrain. Read the disclaimers about the tours before signing up, but if you can do it, it is well worth it.
Wahweap Campground in the Glen Canyon Recreational Area is really nice and close to the town of Page, Arizona, where most of the tours go.
Horseshoe Bend is really close and worth a quick visit. You do have to pay to park there, and there’s a bit of a walk (flat, but it could be hot in the summer).