I have been on all sides of this. I have advocated both a Christianizing strategy and an ignore it strategy. The ignore it strategy is based on the reality that no matter what Halloween may or may not have been in the past, it is certainly not a Christian holiday today. Therefore, it should be treated like all other non-Christian holidays: ignore it. When I have adopted a Christianizing strategy, I have tried to give a Christian focus to it, usually harkening back to Halloween's partial origins in All Saints Day Eve. Using this strategy, I have had my kids dress up like saints to attend a church sponsored All Saints Day Eve/Harvest party; or, if no church party is available, I have even taken my kids on a limited Trick or Treat canvas of known and trusted neighbours. This Christianizing strategy did not come into play until my children were in public school. Before that, I pretty much had an ignore it strategy. And once I began to home school my children (when my oldest was in fifth grade) we gradually returned to ignoring Halloween.
I think ignoring Halloween is ideal, if you can ignore it without causing your children to suffer more than they are able to endure with joy. Yes, I said with Joy. The hymn to St. John the Baptist says, "... and after suffering with joy on behalf of the truth..."
It is easy for parents to impose ideals on their children, ideals for which the parents suffer very little and for which the children suffer a great deal. Parents must be aware of what their children may be suffering--especially at school out of their presence, and realize that suffering without grace will result in bitterness, not saintliness. Certainly if the children are home schooled, it is easy to ignore Halloween. However, if the children are in public school and everyone in the school dresses up, then discernment and perhaps compromise is called for.
Of course there is more than one way to deal with this problem. My main concern is that Christian parents not, for the sake of their own piety, unnecessarily cause their children to suffer. If a parent is very convinced that their child should not participate in any Halloween activities in the public school, then perhaps it would be a good day to take off work and spend with your child(ren) doing something they enjoy. Go to the zoo. Take a picnic. Visit a natural history museum. Take the suffering on yourself by losing a day's work for the sake of your piety. Don't force the suffering unnecessarily on your children.
I realize not everyone can take a day off work for their children (although many could who do not admit it to themselves--just thinking about your children's suffering may be enough to make you ill enough to call in sick). Some may just have to compromise--for the sake of their children's salvation. What exact compromise will be life-giving depends on the family and the circumstances. And I imagine each year will be different--it certainly was in my case.
One thing is certain. Those of us who ignore Halloween should not judge those who compromise with it. In 1 Corinthians 13, St. Paul says that "Love believes all things." I think that means that love believes the best in and of others. I believe that those who ignore Halloween and those who don't are doing the best they can in the circumstances they find themselves in. Perhaps it is a lot like the meat-sacrificed-to-idols issue St. Paul deals with elsewhere in 1 Corinthians. Compassion and concern for the other is called for.