I would definitely do
MVMCP - preferably on a week night. It might be a little less crowded! I would think that the earlier in the week you went might be better. Not sure where we'll be eating at on the night we go - we tried LTT before
MNSSHP last year! It was pretty good!
I would also suggest doing the Candlelight Processional at Epcot, and getting the dinner package, if you were going to eat at a World Showcase restaurant anyway. My family loves this show; we usually eat first, then see the show, then Illuminations!
Be sure to resort hop and see the Christmas decorations! The tree at the Grand Floridian is unbelievable! And there is a gingerbread house at the Grand Floridian too!
My family enjoys the Crystal Palace at MK - its got the Winnie the Pooh characters!
The Osborne Lights at MGM is also really good to see! When you check in at WL, they'll give you a list of what's going on at the hotel too!
You may want to check into having a basket delivered to the room for your son. I had Disney Florist deliver a basket for my DD last Oct and the card was signed "Mickey and Friends". She loved the idea that Mickey would send her so much stuff (the basket included a disposable camera, autograph book & pen, stickers, stuffed Mickey, some snacks, and a balloon) It was waiting for us in the room when we got back from Downtown Disney on our first night! Maybe you could try for a "Christmas" theme to your basket!
Have a great trip! By the way, we'll probably be at WL Dec 8-12; so we'll just miss you too!