Since the majority is for Barcelona, I suggest we go from there and start to narrow it down to dates.
Well, I wouldn't be so fast to conclude that everyone wants to go to Barcelona. In a poll like the one on this thread, no one can express their second or third or fourth preferences. We run the risk, therefore, of ending up with Arrow's Paradox, where the most popular choice is the one that doesn't get the most votes. For instance, if those who voted for London and Munich would have listed Vienna as their second choice, then more people would prefer to go to Vienna than to Barcelona.
Before relying on the poll, therefore, the second-order preferences of those who did not vote for Barcelona should be gauged. For instance, if I were to rank order my preferences for an A2K gathering in Europe, I would put them in this order:
I wouldn't even list Barcelona, since there are no A2Kers who live there. If Vienna weren't an option, then, I still wouldn't vote for Barcelona -- not that I have anything against Barcelona, just as I have nothing against Rome or Stockholm or Prague (all cities that I would rather go to than Barcelona, but which also don't have any native A2Kers), it's just that I put a good deal of importance on the value of having some local knowledge available. My preferences, however, aren't reflected in the poll, just as no one else's are either.
So, in other words, just because Barcelona has the most votes doesn't necessarily mean it's the most popular choice.