Hi Lisa! Halloween is certainly a celebration at Walt Disney World and it actually begins in September when the
Mickey's Not So Scary Halloween Party dates begin. This special event party in the Magic Kingdom is offered on specific nights and runs through the Halloween weekend.
The place that seems to celebrate this holiday the most is certainly the
Fort Wilderness Campground Resort. The guests who come for this time of year go all out to decorate their sites and be in the festive Halloween spirit. The 2016 schedule has not been determined yet but in the past there will be a dog costume parade, pumpkin carving contests, and site decoration contests. Either the day before or the night of Halloween there will be a golf cart parade where guests have taken time to decorate their carts with a Disney Halloween theme or something else. There can be more then 100 carts and guests line the roads of the resort to cheer on their favorite. Once that has finished then trick or treating begins.
These activities are for the guests of the resort but others can certainly come and enjoy them as well. Parking will be next to impossible so take the Disney transportation.
One last thought is to also come and enjoy the Halloween movies after Chip and Dales Campfire Singalong. Some years a special guest might come and surprise you!