I grew up going to disney twice a year. One of the perks of living in florida.
1. December can get slightly chilly in central florida, but more then likely it will be in the 80's. So pack shorts and t-shirts, and jeans and long sleeved shirts in case it is chilly. And do NOT forget sunscreen. The cost of it in the park is outrageous! Wear comfy shoes, and bring tylenol-your legs and feet will be very sore at the end of the day. You also might want to bring along raincoats and rainboots. It really sucks walking around disney soggy. Put them in a locker at the beginning of the day so you dont have to tote them around.
2. You can get cups of ice water free anywear they sell fountain drinks. You will not believe how much $ this saves you on bottled water!
3. To save $ only eat one meal at the park. And if it is a sit down place, call the DAY BEFORE to make reservations. Or you won't get in. The Crystal Palace is WONDERFUL! 20$ buys you an all you can eat buffet of prime rib, salmon, roast chicken, comfort foods, salads, fancy desserts, vegan cuisine, kiddie food(like a peanut butter and jelly sandwich station) and much more. PLUS it is a character restaraunt-Winnie the Pooh themed. They have a Pooh parade for the kids to participate in. It is worth every penny. But call the day before!
4. You can ask to sit at the front of the monorail. Kids get a kick out of it. Great view.
5. Take a break midday and go back to your motel room. Have an hour nap, then go back. You will be amazed how exausting Disney can be.
Have Fun!