I've just been searching through and looking at some of the great road trips and photos here, like this one and this one.

Just thought I'd mention that there is a site called MapVivo which enables you to plot a route on a map, adding images to different points as you go to give a much more spatial feel to the trip - and it calculates the mileage also as you go. You might want to check it / use it for future roadtrips: http://mapvivo.com