I'll make one main comment on your planning, and this comment is ENTIRELY based upon my personal preference. But consider whether it applies to your family as well.
Personally, I couldn't imagine spending an entire day--8am to 10pm (or whenever)--in a single park. Yuck! You might need that type of "commando" touring in order to visit all of the parks during a 4 or 5 day stay, but with 12-13 days in your trip, you have pleanty of time to spread things out.
At the very least we split our day into two time blocks which span morning/early afternoon and late afternoon/evening. I prefer to take a more intiutitve approach to planning (or NOT planning) a trip. Make your activites flow from one to another rather than saying "Today is our ONE day at MGM, so you better do everything you want to do."
If it were me, I wouldn't even be asking myself whether AK or MGM is the two-day park. The immediate answer would be to spend 1 1/2 days at each.
A lot of the things that you have on your list can be combined in a manner that makes a little more touring sense.
For example, even during peak seasons, Animal Kingdom will close at 5 or 6pm. What are you going to do with those evenings? How about touring AKL (while in the area) or visiting Downtown Disney.
A full day for touring resorts? I think your children will probably make you reconsider by the time you hit your 3rd resort. Why not tour resort areas while you're in the neighborhood? For example, hit MK in the morning, have lunch at Chef Mickey's, then tour the monorail resorts.
Disney has an excellent transportation system. Don't feel that you need to spend your entire day in one location.
I'm assuing you'll be getting Annual Passes due to the duration of this stay. So you shouldn't have a functional need for "non-park" days. Even if you want to plan some down-time, mix at least a few activies into your day.
Lastly, I would personally suggest that you purposely leave a day or two near the end of your stay as "unplanned." You can still "plan" everything you want to see/do in the first 11 days of your stay. But leave those last couple of days for your family to reflect on what you've done up to that point and decide together how to spend the remainder of your time. Perhaps everyone will want to go back to a water park again. Or maybe they will want to hit specific rides for a 2nd (3rd, 4th, etc.) time.
Planning is great. I love planning. But give your family time to be spontaneous--even if you have to plan the "spontaneity."
