Noni,
All four parks have something that both your kids will enjoy, but of course the Magic Kingdom will have the most of all. I would recommend that you plan on twice as many days at the Magic Kingdom as you would at any other park.
Another pointer that might help you plan is to look at the
web page that Disney has created to help parents of younger children. My favorite item there is the Magical Beginning maps that you can print out. They show, by park, some of the main attractions that would be appropriate for your kids and that you would want to make sure to visit.
This page has a lot of other great places for you to start your planning. Make sure to read about the Baby Care Centers, in particular. I find those especially valuable resources that most guests simply don't know are there!
After you have reviewed that information, come back and ask us your specific questions. We can help with recommendations on restaurants, experiences, attractions, you name it! If you want to ask a specific panel member directly, just go to their bio page on the site.
Have a magical vacation!