6 week trip itinerary - but I have some specific questions

we did a trip like this from the west coast a dozen years ago .
we needed extra days in mesa verde , arches , yellowstone .
we did improvise along the way and got behind schedule on the way out .
after 4 weeks my wife got very homesick and we rushed to get home the rest of the way .
we did another trip with my wife's folks .
my FIL is a great guy and i enjoy him .
but after an extended trip we were both frazzled .
different priorities and different pace .
plan extra time or reduce the number of stops is my experience .