Going out to the Canyon myself later this year. Plan on taking 3 weeks to do it. 1 week out, 1 week there, 1 week back. Will be retired by then so that makes it easier. In my car or the wife's Explorer, 14 - 16 hours is not that bad. In the MH with the toad, 10 hours is rough. Misplanned one leg on our last trip and a 10 hour drive on one day just plain wore me out. Way more stressful drive when you're long and bend in the middle. People have even less respect for RVs than they do for 18 wheelers.
Over the July 4 holiday, it's Cherry Festival in Traverse City, Michigan. That's a nice area as well and the crowds are isolated into certain areas so is easy to maintain your crowd tolerance level. Some nice wineries up that way as well.