Based on the ages of your kids, I would do:
Magic Kingdom - 2 day from open to close
Epcot - 1 LONG day
MGM - 2 days
Animal Kingdom - 1 day
Magic Kingdom is pretty big and has so many rides that both adult & kids of all ages will enjoy. Now that we go with my daughter, we find that we spend more time there (4 days out of 9). You really have to go to Epcot but, I just don't think it is the best kids park. However, it is big so, you should plan to be there from open to close in order to get everything in. MGM is another one that is fun for all and should be easy to do in 2 days. In fact, if you can do it in 1 day you can add another day to another park. Animal Kingdom is my least favorite but, again, you have to go. Because they close so early each day, you need to plan it for a day when you can be there at opening. That way you can ride everything and see all the shows before closing.
Best Wishes.