Turns out Mark Sanford wasn't hiking, he took a solo trip to Buenos Aires.
It's eccentric, to be sure, but I still maintain there's something cool about that. Don't lots of people spend a fair amount of time fantasizing about making a getaway like that? If you can't show any harm done to the peoples' business, and his family doesn't care, I'm not sure what the big deal is.
(That said, after a planned trip there with friends fell apart last December, I myself considered going to Buenos Aires solo, and decided it was perhaps a slightly odd city to visit on one's own..)