When driving up Mount Rushmore out of Keystone the highway will pass to the left of the Monument and once you start down the back side of Mount Rushmore the road straightens out a bit. I suggest that you pull off the side of the road at this point or find a safe place to turn around and drive back up hill. At one point "Clinton Rock" will be dead ahead of you on the road. If one uses their imagination a bit, it seems that the rock to the left of Wilie's Willy could be fashioned in to a likeness of "Monica".

 

I did the same journey 3 yrs ago, take your time and enjoy, VA-Matt has the right idea; also stop at each state visitor's stations they are also very helpful. I really enjoyed my travels along Route 66. The route through norther AZ to Oakman was really beautiful and driving the twising and curving roads was a lot of fun. But remember alot of that area is also open range land and you can come upon caows, donkes, and other wild life anytime. Let us know how the trip goes