Once upon a time, barnstorming over the countryside in a biplane was sufficiently thrilling and expensive for the idle rich. Then, the only thing that would do was taking a steamer to Africa to blast away at lions for the season. Then there was (and remains) the curious habit of paying a small fortune for the privilege of expiring on Mt. Everest from hypothermia, oxygen deprivation, or stumbling into a crevasse. Much later, attempting to circumnavigate...