Myself and the FPO have been considering doing the Route 66 road trip next year (at the moment it's that or Japan), and saw the Billy Connolly TV series when it was on, to help whet our appetite. I have also just finished the book of the series, and it's made me want to get out there and explore (and meet people). The route and stops that Billy did are easily manageable in a month or three weeks, but obviously, the longer you have to do it (and the more money), the better it would be. I love the USA, but there are still plenty of places l haven't been to, both there and abroad (like Japan), so we will have to see how it goes.
I suppose l could always do a 'Vanishing Point' kind of trip and travel it as fast as possible, and with minimum sleep (3 or 4 days?), but that would be a different experience altogether, and l would have to go back to illegal substances (what a sacrifice). Not sure if the FPO would be up for that kind of trip (in both senses).