We made a trip cross country two years ago and stayed in those national parks around the Four Corners states - Mesa Verde into New Mexico, Utah and Arizona - for about six weeks. Two older adults, no kids. It was one of the best trips of my life and I'll never forget it.
Consider starting with a one day course at Crow Canyon Archeological Research Center near Mesa Verde. They are family oriented with hands-on activities and lots of time outdoors including a visit to a dig. A young boy in our class seemed to enjoy himself. It was a really fun and educational immersion into the history of the Southwest's Ancestral Puebloans. So many places we went built on what we learned, such as Mesa Verde, Salmon Ruins, etc.
Kids really enjoy Goblin Valley State Park where you can walk around amid weird rocks and camp overnight in a beautiful setting.
Get the Indian Country Guide Map from AAA (you can find it online.) Really great for mapping a route and what not to miss along the way.
Stay often in the National Park campgrounds, which almost always have ranger talks and handy hiking trails. Book early to get a site in Zion's Watchman CG along the river with electricity. The shuttle is close by and there are numerous ranger activities.
At Lake Powell near Page, AZ, you can camp by the lake at Wahweap. Take a boat ride on the lake to see the Glen Canyon dam from above. Then tour the dam inside - great tour! And finally, take a river day raft trip down below the dam on the CO river - suitable for kids, no problem - an incredibly scenic float trip with a guide.
Planning gets the fun rolling...have a good time!
