Great report and photos! What software do you use for filtering and resizing? Kudos to you and your wife on bringing the little ones along on such a long road trip. The longest trips I did with my son and daughter when they were that long was only about 4 hours (Orange County, CA to Anza Borrego Desert State Park, CA). I waited til my son and daughter were out of diapers and they didn't need a baby seat (takes up so much room) when I started the big trips.
Bummer that you were on the road when my son and I made our trip and didn't get to read about our report on Hardscrabble Camp's bugs. It was pretty overwhelming to say the least but we at least had bug spray. As you probably did too, we had the entire Hardscrabble area to ourselves and while we had Camp A reserved, we drove down to Camp B, to see if it was better in terms of shade and less ants (Camp A was on top of an anthill). We thought Camp A had more shade and we remedied the ants by strategically placing a few Twinkies away from our camp which they all migrated to.
Arches NP is great! There is a great side trail going east-west into the park off of Highway 191 that has dinosaur tracks on it too. I can't remember the name of it but I'm sure someone in this forum knows.