Grand Canyon or Yellowstone for 2015?

We spent a week twice at the North Rim of Grand Canyon and found plenty to do both times. Maybe there is more to do at the North Rim, it's been many years since I visited the South Rim. It's too crowded for us. It helps if you have a 4WD truck, I have to say, since that opens a lot more of the park roads.

There are very few parks that can be covered in a few hours. Devil's Tower is one and Rushmore is the other I can think of. If you are satisfied by driving a loop road and checking the park off you list then I guess you could add many more to the few hour list.

BK