Im looking to do a one-way trip to Oregon this summer and was wondering how many days I should set aside for the drive.

I am planning on stopping at 3 places along the way...Field of Dreams in Iowa, Mt. Rushmore, and Yellowstone. I am just curious if anyone has ever taken this trip, what the best route to go would be (im thinking US 20 for part of the way) and how much time I should ideally spend at each location along the way. Any help or advice would be apprecaited,

thanks