We're at Fort Wilderness the night before (30th) for Trails End and Return to Sleepy Hollow (which could be an option for you guys on Halloween, it was $22) and apparently they have a golf buggy parade where every one decorates their carts. We're also planning to look around the campsites at the decorations. The cast member I spoke to was ecstatic about the decorations at Fort Wilderness.
For Halloween we'll be having dinner at Beaches & Cream, then hitting up Abracadabar and Jellyrolls and hopefully, other people will be dressed up.
There's plenty of non-park hotel options you can do but the hotel activity schedules won't be out until October annoyingly.