With that age children, if your budget can swing it, I would go for a monorail hotel. You will probably spend most of your time at the MK and that puts you very close with easy access to the park and your hotel for naps. Of the monorail properties I would choose the Poly. That being said, if a moderate is more in your budget then our recommendation would be the POFQ for the following reasons:
1) Smallest resort of the moderates, easy to get around, everything is close.
2) One bus stop for this resort. Sometimes it shares with POR but at FQ you are the first on and the first off -- nice for the little ones.
3) Boat to DTD. The kids will love it and DTD has some fun things for the little ones. If you go the first of Dec Santa is there for pictures, etc.
4) The pool area theme is perfect for that age. My DS loved the alligators with all their music and the slide is great for the 4 year old if they swim. The kiddie pool is nice, also.
5) The playground is perfect for that age.
6) With kids that age, though, a ground floor room is really nice as you don't have to wait for an elevator but we've been on all three floors. They are nice.
7) Moderates now all have refrigerators in room at no charge.
8) You can go down to POR and do some "Huck Finn" fishing for a small fee. Your 4 year old will love it. You rent the poles and buy the bait. Warning you get to put the live bait on the hooks.
9) The food court at POFQ is smaller than the rest of the moderates so is a bit easier to navigate with little ones but it has a nice selection of foods.
10) There are ducks and birds as well as squirrels by the river at the resort. My DS at ages 2-6 loved to walk along the river and watch them.
The weather, at least the first of Dec/end of November can be very nice -- in the mid 80's during the day and drop down to the 60's at night. That being said -- we have been there when it has hit the high 30's (with all that humidity it is cold) for a low -- brrrr!!!! There was not a hat or gloves to be found on Disney property. Thus, we plan for all types of weather and LAYER everything. But, overall, it is nice weather.