How is it possible that you both have an unlimited time to undertake such a trip? This would sound pretty ideal to just about anyone of the regulars on this forum! I moved your thread here, because such open-ended trip planning usually makes more sense here -- and welcome to the Great American RoadTrip Forum!
The first question I have is how much $$ do you have for such an adventure? It's rare, (perhaps it's never happened before) where the most valuable commodity we deal with around here -- time -- is under no limits. You can drive coast to coast in five days or five years -- What sorts of places, attractions, etc are you looking for on this epic trip?
Mark