[Trip]

14-21 days you have a lot of time to do a lot more, I did my trip all the way out to Cali in about 15-16 days if I remember right.

If I were to do something close to that with going the Northern route first.

I don't know anything about Minnesota/Wisconsin/Meeechigan, so I will start in South Dakota.

Badlands is worth a ride through, cool place. Skip Wall Drug Store no matter how awesome the billboards are...

Skip Mount Rushmore, do Devil's Tower instead...

Bighorn National Forest on highway 14 is pretty freakin cool ride. If you are going to go into Yellowstone, take highway 212 from Red Lodge into it. Beartooth Highway, one of the top ranked rides in America. I didn't get to ride it in early June, it was snowed over. Check the snow on your roads even in the late May. I went through that area in early June.

I'd try to swing a little further west in Colorado as you go south from the Rockies and hit the San Juan Mountains in Colorado, 550 Million Dollar Highway. Pretty cool towns through there. You could hit up Mesa Verde National Park if you like cool old human structures on cliffs.

What are your must sees on that route?

Also, try and hit more highways than interstates out west, you will be amazed how much time you can make on them out there. A lot cooler stuff off the interstate.