uh oh, worldcon writes again

I voted for the Hugos. Now the Worldcon writes to remind me that I have one day left to vote for site selection if I want to. (There's on-site voting also, but I'm not going so that's irrelevant.) That's if I want to get a $40 supporting membership in whoever wins.

Do I want to? And who should I vote for, D.C. or Helsinki? (The other two are not on, in my opinion.)