Halloween falls on Friday the 31st. The last event was on a Saturday and had a good amount of people.
I neither have kids, nor live stateside, so please let me know which date would work better for you wrt you being able to attend trick or treating with your kids. The goal here is to let you have fun with your family and finding a time that works for players that doesn't interfere with family time.
It *may* be that everyone will be out with kids on Friday, but I'd rather ask and make sure instead of assume.