I'll be driving too. There's no max or bus that runs all the way out where I live, and leaving my car in Sherwood on Halloween doesn't sound like a good idea.
My car can fit 5, so if we decide to go somewhere within a few miles, I'm up for it.
Anything far away though, people would need to chip in for gas.
I think there'd be a lot to do within walking distance, though, like what anime_gurl suggested. It's PORTLAND afterall.