Definitely consider visiting Canyonlands, it's like a sister of the Grand Canyon but less crowded. There's plenty to see and do, including viewing roaming bison, looking at underpasses, and great views of the needlepoints. There's also a section where there's primitive trilobytes, and depending on when you visit, you'll be able to see the rock that appears to stand up on a tiny tip. Really worth seeing as it contains hundreds of canyons, each with different textures, depending on which side of the park you start driving into.
Zion NP is one of the most beautiful places to visit ever. There is a bus shuttle that regularly picks up and drops off visitors, and many visitors will stack stones up to mark their trail. You'll also see raindrops in some parts of the parks, even though it's completely dry. Breathtaking to visit!
When visiting Moab, make sure to visit all of the Arches. The view is incredible, especially with a rainbow in the sky. There are some Arches where you're not able to walk within 250 feet of it due to it being fragile, but the rest of the park is the natural formation for generations to enjoy ahead.
This is a great place to stop in that it is close to Camp David (historically presidential location). Make sure to drive slowly, as the road to get there is very curvy and somewhat steep grade (if driving eastbound. Recommend using fog lights.
The drive to Rocky Gap is really relaxing, and a good view of the casino from across the water. There is also lots of space for picnics and celebrations. There are several places to rent a canoe, but have to from outside the park.
Adventurous, in that you'll get a first-hand glimpse of the horses, as they are aggressive! Very nice Visitors Center where you could request a ranger badge for the little ones. Would recommend visiting in late summer, early fall to avoid the crowds.
The park is really good for adventure seekers. The horses aren't afraid to come up close and personal! Would recommend visiting in late summer, early fall to avoid the crowds.