Here's another in an occasional list of essential road trip experiences: 21-25 (in no particular order):
Stay at the Devil's Tower National Monument KOA in Wyoming. Watch Close Encounters of the Third Kind under the shadow of the tower and keep an eye open for strange cloud formations that hide UFOs.
Sleep one night in your car or, better yet, under the stars. Naturally you need to concern yourself with safety and respect for private property, but seek one opportunity to avoid the constriction of formal lodging.
Drive through a righteous electrical storm (not on purpose, mind you). Slow down to a reasonable speed and watch the lightening fill the sky.
Listen to an audiobook of a title you'd never have the patience to read otherwise.
Memorize a great poem or lines from a favorite speech. Practice it during long, boring stretches of road.