I've got a party to go to already, a Birthday party! My friend Becca was actually born on 10/31 so she gets to take over the holiday every few years instead of having a party on a convenient weekend day. She gets even more control over Halloween this year because she runs the every-other-week roleplaying game that would have fallen on that night in the first place.
Oh, and I don't think that cosplay trick or treating really counts, you HAVE to be in costume to trick or treat! That's like "behind the wheel driving".