We avoid all extruded and/or "puffed" grains. They are carcinogenic and not part of man's traditional diet. I know that you are asking for the sugar aspect, but this is another take on it. We do occasionally (rarely) have a rice cake in my house since we do crave crunch and are phasing out corn at this point (we've already eliminated a long list of other things like sugar and wheat entirely) but I would not advise eating any cereal, especially for small children. Sally Fallon's book, _Nourishing Traditions_ is an excellent one if you want a diet that ensures optimal health for yourself and your children. We found this book because my youngest was born with no enamel on her baby teeth. We have successfully healed her caries with diet changes and we all feel more energetic, have better mood, and even have shinier hair and less aches and pains.
We also don't consume cow milk, at least not in the state it is sold in stores here. I would drink raw milk if it were available and we do eat raw cow cheese and some goat milk, but if you're looking for calcium look toward other things like dill, broccoli, etc. Any cardiologist will tell you that milk is really terrible for your heart, and anything with powdered milk is even more toxic due to the processing.
I hope I don't sound preachy, but I do hours of research on foods every day since both of my daughters have different health needs, and I hope you will take the time to do some reading on these things- you will truly be amazed!