In our district we done technically celebrate Halloween in our classrooms with a traditional costume parade like we did when I was a kid. Now we have "Harvest Parties" which fits because our school sits beside a HUGE corn field.
For a few bucks at Walmart we had a LOT of fun being silly and having a GREAT time!
We had a GREAT time having yummy snacks and acting all silly. :) Complete with "It's the Great Pumpkin, Charlie Brown"