We've been a few times the first week of December, and the Pop Warner kids aren't an issue in the parks. MGM was closed at 6 PM on the Friday of that week for a private function for them. Otherwise, we saw only a few small stray groups of them in the parks at various times, hardly a crowd. The people who seemed to have the most issues with them were the people who stayed at the same value resorts that the kids did. They can reportedly be very loud and boisterous and cause crowding at the pools and food court. If you stay somewhere other than where they are, I doubt they'll have any impact on you. Re: the weather, as has been said, it can be all over the place. When we went last year, that particular week was in the 80's the entire time, but the weeks just before and after were quite chilly. Since no one has a crystal ball, your best bet is to check the long range forecast for the Orlando area a day or so before you leave. It will give you a good idea of the weather pattern for the next week - whether it will be generally sunny or rainy, and whether temps are predicted to be significantly above or below normal. We did that, and when we noted the exceptionally warm forecast, we were able to pack accordingly and take only minimal cool weather clothing (which as it turned out we didn't need at all). This will really help you pack appropriately, rather than trying take enough clothing of both types to get you through your stay.
). Last year we went 11/10-11/14, and it was great, not alot of people ( although 11/11 Vet's Day slightly more people, but not a big deal) we would have gone then again, but they have changed the value times. 
