I have never been to WDW during president's week but I have been to WDW about every other time and I don't think it will be too outrageous fighting the crowds. The one thing to remember with kids your age is to take an afternoon break. It doesn't matter what you do....go back to your resort for a swim.....take a nap......stroll around a resort you have been wanting to see.....whatever. Just get away from the parks and the crowds and take it easy. You will be able to replenish your energy so you can go into the early evening and the kids won't be as cranky. Personally, I am a fan of both the swim AND the nap for two hours or so.....you won't believe how it will relieve any stress and tension the long continuous days can bring.....for everyone in the family!