For us, it seems like a lot of miles. I would agree with magnusfide, I'd pick a few places and enjoy the trip. I'm just curious about your itinerary. You seem to be spending a lot of time in Las Vegas. Is there enough to do in Vegas with a 10 and 12 year old for three days?
If it were us, Day 2 and 3 would be 1 day. Doesn't appear like you are doing anything on those days other than driving, so why not combine it? You're in a motorhome, so less than 900 miles is a good day of driving. We do 800 miles in our motorhome (Georgia to New Jersey) in about 13 hours a couple times a year. I would be too restless at the end of day 2 knowing I still have 400+ miles to go the next day and could easily get it done that day.
For us, I think we'd break this trip up across a few years. I'm sure it would be a great trip, but I know we'd be saying, "I wish we could have spent more time at this spot, etc.".
-Michael
