I just finished a long road trip from So Cal with an adult daughter. We visited Yosemite, Tetons, Yellowstone, Devil's Tower and Deadwood. If you get the chance, visit Yosemite. I found that much more interesting than Yellowstone. Incredible visual experience.
In Yellowstone, at same location of Old Faithful, visit the old Yellowstone Lodge. Very interesting. Weather permitting, there is an open deck on the second floor that is open to the public. Nice place to sit and relax.
Have a great trip!