Are you a DVC member? They are doing two members only Halloween Parties at the Contemporary, the party from 2-4pm sold out super fast but there is a party from 7-9pm that we were able to get tickets for (not sure if it is also sold out already). It was $15 per ticket and will have some desserts and drinks, characters, face painting, dance party etc.
We are staying at BLT as well so we plan to go to the Top of the World lounge after the party for the 10pm fireworks.