They usually trick or treat, but I think we've had enough of dragging them around in the dark when it's raining, cold and one or the other is misbehaving. Church is having an indoor kids' carnival Halloween night, so that sounds good to me.
Make costumes? Wish I could. Not creative and no sewing ability. I've bought costumes cheap at StupidStore and Liquidation World before. I think they can probably pull something out of the closet from last year.
I'm a huge bah-humbug about classroom parties at school. I mean, c'mon...we send them to school to learn, not to run around and get jacked up on sugar.