Definately go to MVMCP. We went Dec 5-11 and stayed at the AS last year, same rate, too. Watch MK on Saturdays because they film the christmas parade (we saw regis and kelly!). It was totally packed and hard to get down Main Street. The place we stayed also had the Pop Warner cheerleaders running around everywhere. Hopefully you'll miss them.
Bring clothes for all seasons. It was freezing at night, but moderate in the afternoon. We didn't go swimming at all though, but some other people did.
The crowds weren't all that bad, but at MVMCP they are awesome! After the first parade all the people cleared out and we just walked onto any ride we wanted for the duration of the night. It was magical. I can't wait till we go back in 2005!
When we were there carousel of progress and timekeeper were both up, but I heard they will close when Stitch opens. Oh, and at MVMCP you get free hot chocolate!
Epcot is cool too during those times. Definately see the candlelight processional. Its not very "exciting" but very Christmasy, and my DH and I enjoyed it. (We didn't get the package). Its also cool going to all the countries and seeing the different Santas.
I'm so excited for you! Have fun!