I don't have any advice, but I'm very curious to hear what others have to say since we were trying to decide between these same 3 weeks as well!
I think we're leaning towards arriving the Sunday after Thanksgiving and staying thru Saturday. So, not quite the first full week in December.
From what info I've been able to get, it seems like that would work out best.
We'd like to avoid the Pop Warner crowds and don't want to have to plan around the Christmas Parade taping at MK. I'm willing to miss seeing the big tree up in MK to avoid those other things.
The one thing I haven't been able to check into yet is how the airfare prices will differ between those weeks. With Thanksgiving being such a popular time to travel, I'm not sure if flying on a different weekend will save us enough money to reconsider what week we choose.
Good Luck!