BTW -- and understanding that ship has sailed -- the old system with the rotation zones and a three year lag between the vote and the con had a lot to recommend it. Fans who were only likely to attend a Worldcon in their zone would end up voting every three years for a Worldcon bid in their zone (or overseas, but if the Worldcon went overseas, they'd end up with a Supporting Membership to vote for the next time their zone was up in rotation).

It's possible to argue, of course, that people should buy a Supporting Membership (at least) in every Worldcon, but that's a not-inconsiderable chunk of change, as we were discussing in another thread. :)