If they want to come back to the 'States, I'd like to see them go to Kona and do a "driving man's" version of the IronMan triathlon. Instead of running, they could drive, instead of swimming, use boats, use jet skis or motorcycles instead of bikes, that sort of a thing. Though Kona is expensive for a location shoot, the scenery would be fantastic.
Of course, they might have trouble with James getting lost-don't want him to fall into a volcano. Another problem might be the Sat Nav-could be pretty useless there for them, with all of the street names something like "Kealakekua" which, I'm sure they would have a hard time following. (Imagine having to call the auto club, only to say, "I'm stuck at the corner of....Keal....Keal...um...." Almost every street is the intersection of unpronounceable and impossible to spell really. Still, you know, the scenery and all.
I'm sure this has been suggested before, but, just in case.