Make sure you tour the resorts to see all the decorations - the huge gingerbread house at Grand Floridian is amazing. My DSIS and I saw the Candlelight processional at Epcot - don't miss it!! My suggestion though, we didn't go to the extra expense of the dinner for priority seating - we just waited until it was time looking around in the gift shops, then stood at the back behind the rope - saw the choir go in right by us, and we heard and saw everything perfectly, plus we were the first ones to leave it before the crowd poured out. The Osbourne lights are a must as well - we saw them three times and could have wandered around there for hours in amazement. All the trees at the parks and resorts are incredible, and make sure you do character greets, especially at AK in Camp Minnie Mickey - their holiday attire is so cute!
Enjoy, we loved it at Christmas time!