Last year we drove to St. George Ut and back. We took 3 weeks and visited just about every national monument and national park plus a myriad of historical locations along the way. The scenery was amazing and we got to see many places that you read about or see in movies, but in person. Wherever you end up going, do your research first. Frequently there is much more to see than the main attraction.
If you are interested in the roots of western civilization, I recommend the 14 day Mediterranean cruise we did. Rome, Naples, Medina, Crete, Santorini, Kotor, Istanbul, Kusadasi, Barcelona. The layers of history from the Phoenicians and Minoans, to the Greeks, Romans, Venetians, Ottomans, WW1,WW2, it's all there. Waking up on our cruise ship in the flooded caldera of the Thera explosion in the harbor of Santorini, the largest explosion in recorded history was incredible. As a history buff I can't say enough about this trip.