We were there last Dec. and LOVED WDW in Dec.! We are going back this year.
Like PP said, I would def. set time aside to go see the resort decorations. BWV and BCV are two of my favorites!
Look into all the special holiday events at each park (i.e., Mickey's Very Merry Christmas Party at the MK, Candlelight Processional at Epcot, Osbourne Lights at Hollywood Studios, Jingle Jungle Parade at AK, etc...) and decide if you want to go to them b/c some require special reservations or tickets.
We stayed at OKW and BCV last year, but we'll be at SSR this year. I think it is a perfect location in Dec. b/c you can walk to DTD and do some holiday shopping, see Santa, etc....
If you have more specific questions about anything, let me know. I would be happy to help!