I think the only fair thing to do is to give them all finales. And if you don't call that the hot-coffee update, I'm going to be very disappointed.
You could keep your life simple (and free) and put the scooby gang in The Void. After all, we already have a witch and a mummy there to chase them around. The void gets a lot less void-ey if you throw in a couple large props behind your players to decorate a bit. And you'd probably be able to turn that around on time for halloween.
Speaking of halloween, I was thinking of updating Sandra's witch outfit, but she came in dead-last in that poll, so I guess I should do something else? Maybe Leah can get costumed up, since she's the only one without a special outfit? Thoughts?