Can't make it this year, but we've been at Poly LV Concierge during Christmas season 1996-2001. You will LOVE it!
Here are a couple of tips:
If you have tickets for Mickey's Very Merry Christmas Party, and you go back to the room prior to the party - take the BOAT (not monorail) to the Magic Kingdom. You'll probably be able to get in early while monorails are held at the Transporation Center until just before starting time.
Pack a little something for every kind of weather. In 2001 the temps were in the 70s at night in mid-December. On New Year's Eve 2000-2001 the area had record lows with nighttimes in the 20's !!! When the stores sold out of gloves, people bought socks to wear as gloves. I saw people wrapped in blankets from the hotels. Bring your coat.