Dont let the time restrictions bother you, we did mammoth cave in KY, then headed west on I40 west and went to Wislow AZ to see the meteor crater, then to the Grand Canyon, then to Monument Valley UT, then Arches NP, then to Rocky Mountain NP. Then back home. 5300 miles in 17 days total. Never felt rushed, had a great time. Went on horseback rides in UT and the Grand Canyon, went on. River cruise in Moab, went on a tour through Gouldings in Monument Valley. We save time by driving long hours (me and my wife take turns driving) then using rest stops for dinner and a quick overnighter. So it really depends on your situation. When we go on vacation, we always remeber this saying "You arent promised tomorrow" ;)