We are looking at that question again with our new ministry to Middle Schoolers. Our church's policy has been no ghosts, witches, or other spooks - keep away from the occult - but OK with "Harvest Festivals" and that sort of thing. We have a new generation of young leaders and kids who are addressing those issues.
CT about 12 years ago published "Is Halloween a Witches' Brew?" by Harold L. Myra, which is a good, middle of the road, look at the issue.
I'm not at all comfortable with Halloween. I think it works only if you don't take the occult seriously, that is, only if you don't believe evil, intentional, direct evil, exists in an accessible, proximate spiritual world, or, for that matter, only if you believe a spiritual world does not exist. We ride on roller coasters and are thrilled by instincts that seek to protect us from falling but that we can provoke because our intellects tell us we are safe. We trust the human engineering of the mechanical device to protect us. But who or what has designed the recreational contrivances that provoke our natural fear of the occult ? Are those safe structures or portals?