We were at WH for Halloween 2013. They held a pool side party in the afternoon but I'm not sure if any trick or treating went on later in the day.
We drove to Celebration that night and I have never seen so many people trick or treating. Everyone was dressed up and they were queuing in cars from the 192 right into the town to get in. So go early if you fancy it.
Next we went to WDW campground and this was so much fun. Most of the RVs were decorated as were the golf carts, owners were sat outside with their candy to hand out and everyone was having a good time. There was a really good atmosphere and my DD loved it. Be prepared to do a lot of walking. I would definitely go again
We also went to a
MNSSHP the next night and had a good time there