8 weeks sounds like a lot of time but the reality is that you will not be able to see much or enjoy the area with your itinerary. Its WAY aggressive and you WIll get tired of driving every other day. How much have the kids been involved in the planning? What things are they interested in? Have them pick out some specific places/things that they want to see and do and plan on a couple of days in that one place to do that with them. We did a big loop trip and we didn't see all that I would have liked to see and we did stay in places for 2 to 3 days at a time. The time goes by TOO FAST.
I have to say that JUST SEEING the whole country is an eye opening experience as to the beauty and diverse landscapes and the vast expanses that left me in awe. My favorite was seeing Devils Tower and Moab Utah areas. Stunning. I say rethink some of the places you're thinking of stopping to add more time to other stops. good luck