My kids - even up to the married ones in their 20's still go trick-or-treating with us! Last year, I had more teens and 20 somethings in costume walking around with me than littles!!
I started my girls off with a little square pillow and then a tote bag, to get them used to cutting straight, following directions, and so on.
I didn't have time to do this this year because I'm babysitting my baby grand daughter (!!!) while her Mommy works.