Welcome to the DIS.
My first recommendation would be to purchase a copy of The Unofficial Guide to Walt Disney World. You'll have plenty of time to study it thouroughly and plan your trip.
Also consider the ramifications of taking the kids out of school for the trip.
If that won't be a problem, the first two weeks of December are at the top of the list. It's value season with lower rates, the weather is better, the lowest crowd levels of the year, and the parks and characters are decked out in their holiday finest.
This is our third year to go the week after Thanksgiving, and after the first year I said I'll never go any other time of year. It is spectacular !
The parks close a bit earlier than during peak season, but you more than make up for it by not waiting in cue lines and fighting your way through the crowds all day. The past 2 years we went, I have not waited more than 30 minutes on any ride. Often it's a walk on with no wait at all.
The weather was warm enough for a day at Typhoon Lagon last year. The weekend after Thanksgiving was in the low 80's.