Too bad you are not getting the park hopper, but being as that is the case, I would not miss AK, it is so much not a zoo. I would do MK, Epcot and AK. If you decide to change and get the park hopper, I would spend an entire day in MK, an entire day in Epcot and Morning in AK, 12/ day and the other half in DHS.
In MK, I would concentrate on Toontown and Fantasyland then depending on the kids stamina branch out from there.
In Epcot, I would concentrate on The Seas with Nemo and Imagination Pavillions first, then head for some of the different countries in World showcase.
In AK I would do the Safari first thing as the kids will see more animals out before it get warm, then make your way towards Dino land area.
I am at a loss just now for smaller kids in DHS, my kids are nearly completely grown and enjoyed all the wilder rides and attractions, so not so familiar with what there is for little ones just now in DHS.
Hope that helps you make up your mind.