I would venture that few people know what Halloween is actually about, short of getting dressed up and trick-or-treating. It is this portion of the modern day celebration that I think should be moved to the last Saturday of October.
The historical Halloween (shortened from All Hallows' Eve) is, as is many things about our calendar, rooted in Christian tradition dating back to approx. the 8th century (unless you want to go back further to some Celtic traditions).
I understand the religious significance to some, and people should feel free to celebrate All Hallows' Eve as they see fit. That said, I feel modern society has created and adapted "Halloween" into something new. I for one spend time with my kids and neighbors. I am asking we make Halloween the last Saturday of October.