A favourite of mine is the free Downtown Disney Halloween event that takes place usually on the 30th and 31st October. With sweets, characters and special live music all free it really shouldn't be missed.
Personally, I think the best time to go to Disney world is Halloween because the weather is lovely, not too hot but still warm. Also, wait times are reasonable. As well as this, you get the chance to catch the Food and Wine festival at Epcot and to see Magic Kingdom all decorated. My favourite thing though, is the at Port Orleans quick service restaurant last time they were giving sweets at the counters!
My favourite thing to do at Epcot is to get a spot sitting by the railings for the firework show. Then, one person go and get some food just before it starts from a country. When the lamps around the lake are lit you know there isn't long to go so settle down so you don't have to move again. We sat with Chinese and Mexican, with churros for dessert and this meant we were fed, and had a great spot to sit.
From 1976 to 1995, the Fulton's Crab House riverboat was named 'The Empress Lilly'. It was named after Walt Disney's wife, Lillian. Though it resembles a full size paddle steamer riverboat, it is actually a building on an underwater concrete foundation.
It's off the menu and has to be ordered at least a day in advance, but the Hong Kong Fish at the Flying Fish cafe on the Boardwalk is an amazing fresh local yellowtail snapper coated in batter and fried whole. There's even a chef's counter in the kitchen so curious diners can see the action.
If you are on a gluten-free diet, be sure to check out Babycakes NYC in Downtown Disney. This bakery is famous for its cupcakes made without gluten or dairy, instead using rice or bean flour and sweetened with agave. Flavors include red velvet, banana-blueberry, lemon and vanilla.
If you take the "Behind the Seeds" tour in Epcot's The Land, you will see experimental growing techniques, including lemons, watermelons, cucumbers, and pumpkins growing in the shapes of classic mickeys. If you eat at the Garden Grill restaurant you might even find the cucumbers in your salad!