We were at BLT last year for Halloween and they had a TON of activities for kids in the afternoon and a costume contest and trick o treating around 5 or 6. Lots of games, dj/music, cookie decorating, free little prizes, crafts, candy, etc. Our 9 year old loved it but it was a very hot afternoon! The event as on the lawn between the Contemporary and BLT.
We also attended the DVC party which was only $15pp last year. They had desserts, drinks, characters, free photos, free face painting and a dance party with Chip & Dale and Donald/Daisy. I would recommend the party if you are DVC but if you aren't I would suggest you check out the event on the lawn during the late afternoon.