I think it's also worthwhile pointing out that a lot of the cost of these kinds of long trips don't grow a whole lot in comparison to relatively shorter trips. Flights are, in my experience, the largest single expense, and so will cost the same whether you stay for a few weeks at each stop or a few months.
It also depends on how much you pay for two residences. if you keep your rent/mortgage @ home that's another major monthly expense. If you find a sublet/AirBnB or something this still applies.
One of the best times to travel is between leases, if you can stand to 'move' twice. Once to storage, go travel, once from storage to a new place.
Much of the cost of airfare can be diffused with airline miles. If you've got good credit you can pretty easily rack up a few hundred thousand miles without leaving the ground. Sites like FlyerTalk.com are a great resource for this sort of thing. I haven't paid for the airfare of any of my recent trips to Japan and Europe---it's all been done with miles, in premium cabins.
