Also, the more info you give us about your family, the more help we can be to you and your needs. How old are your kids? Does your family like the big rides or not so much?
After lodging and transportation, I think one of the most necessary things to do would be to make ADR's (advanced dining reservations) for the table service places you want to eat, whether you are on the dining plan or not. Christmas will be so busy that it will probably be much much harder to just walk up to a ts and get seated.
#1 Decide if you want the dining plan, which might just be a wonderful choice for your family. To get this, you have to be staying onsite and book a package which is room and tickets together. Everyone in the room must be on the
DDP (
disney dining plan) so you cannot get it for just the adults e.g.
#2 If you choose the dining plan, you can download the brochure to get an idea of what places are included on the plan and what the plan itself includes.
#3 Whether your are on the DDP or not, get a guidebook (a PP mentioned the Unofficial Guide and Passporter, I second those recommendations

). You can sometimes get these from your local library if you want to check them out instead of buying one right away. These will have reviews of the different table service and counter service restaurants so you can start narrowing down your choices.
#4 go to allearsnet.com where you can find, among other valuable info, menus for the different restaurants and sometimes pictures of their interiors. This could also be useful in choosing whether or not to do the DDP, as you could make an approximate guess of what each person would eat at the restaurants you choose, and see if it is cost effective to get the plan.
#5 Post your questions, thoughts etc on the Restaurant board here on the DIS. People will give you great feedback and advice. There is also a great thread where people post their pictures of food from all over WDW so you can get a look at the food before you go.
#6 Once you have the restaurants chosen, plan out what days you want to eat at which (taking into account where you will be that day) E.g. "we will be at AK on _____, so that would be a good time to eat at Boma at AKL. Also think about an approx. time you would like to eat.
#7 Now you are ready to call disney dining and make your ADR's! ANYONE can do this 180 days in advance, whether you are staying onsite or not. One of the benefits of staying onsite however is that you get to make all your ADR's up to 10 days of your trip on the 180th day. If you are offsite, you will have to call back each day. (E.g. your trip is 12/20-12/27. Onsite call 180 days before 12/20 and make all ADR's for all days, offsite cal 180 days from 12/20 to make ADRs for 12/20, call the next day to make ADRs for 12/21 etc). This is especially beneficial to onsite guests who want to make highly coveted ADRs at places like Cinderella's Royal Table or Le Cellier because they get a jump on offsite guests.
This seems like a ton to do just for dining, but I am having fun doing mine and am always looking for ways to do more planning

because that is half the fun of a Disney vacation, and makes waiting so much more bearable!
