I know a guy who finished this "project" last year. Some of his trip reports were rather interesting while others read like a big turn-off - at least for me. Such as checking off a whole bunch of Pacific and Caribbean island states without ever leaving the plane, let alone the airport. I would have wanted to do at least a couple of dives at all of those. That's what really puts a country on the map for my purposes.

Needless to say, he's a real expert on TWOV travel now. He also "collects" aircraft types and got to ride a lot of "interesting" equipment during his trips.