Never really had the desire to do it as an adult because my parents took me on road trips a few times growing up. That said, I did have fun. Basically the most memorable one was driving to Phoenix, Arizona then to Vegas, then back to Phoenix (I don't want to explain, but this made sense). On the way there we took a route that went through the upper portion of the country. On the way back we took a route that went through the lower portion of the country.