I've never been a breakfast eater.  Need to be awake at least 3 hours before I can think about food.  But I assume that kids would like something crunchy and sweet for breakfast.  How about a trail mix?  I put raw unsalted nuts, sunflower seeds etc. together with dried fruits - cranberries, raisins, cherries, apricots cut up - together in a bag and toss.  If you ensure that they get meat for lunch/dinner - a sweet/crunchy breakfast might be what they're looking for.  Good for energy and fat.
gale