Things you can do:
* Serve other breakfast foods instead of cereal, or alongside a very small portion of cereal. Most kids enjoy eggs, breakfast meats, and brightly colored fruits. Many love hot cereals, where it's easy to pack in whole grains and also nuts or fruit if you wish. Vegetables may be a harder sell, but try chopping them into an egg dish.
* Hot cereals tend to be much healthier than cold cereals. Most are whole grain, high in fiber, low in sugar; they often add dried fruit, nuts, and seeds. A smaller amount of sugar goes farther because it blends in more. There are many ways to dress up hot cereal by adding things to it. If you don't actually like sweet things in the morning, try savory bowls instead.
* Choose cereals with low or no added sugar. Honey and maple syrup are great alternatives to cane sugar. I find that if I get a lightly sweetened cereal, it stays on the cereal so I'm not tempted to drown the stuff in sugar from a dish. Some articles suggest using a lightly sweetened plant milk instead.
* For people who love dark chocolate, try cacao nibs. They are crunchy, intensely chocolatey, and not sugared. They're bitter, so milk chocolate lovers won't want them plain. But they should go great with dark-flavored cereals or granolas. You could probably make stupendous chocolate milk by blending cacao nibs into sweetened plant milk, for a lot less sugar than buying chocolate milk of any kind.
* Look for cereals with other positive features such as whole grains, nuts, or dried fruit. If you can't knock down the calories, make sure they're not empty calories.
* The younger your children are, the easier it is to fool them. You can buy the junk cereal and cut it with healthier cereal, or keep the box but refill it with something healthier. This is not the best way to teach healthy eating habits, but if you don't have the spoons to fight over this, deception can save your sanity.
* The older your children are, the more they need meaningful choices. A great option is to let them have one junk item per day. Do you want a sugared cereal for breakfast or a sugared dessert after supper? You only get one, but you can pick which you prefer. For the other meal, your sweet thing will be a fruit or a vegetable. This is good because some people really latch onto a certain type of food -- there are kids who adore cereal but don't care much about cake and vice versa.
* For adults, fiber may be a bigger concern. Check out these high-fiber cereals. Note that All Bran Buds is stupdenously high in fiber but also somewhat high in sugar, so consider mixing that with something lower in sugar. You can also add fiber to any cereal via nuts, seeds, and fresh or dried fruits.
* Softcore: mix your own cereals. Buy a healthy cereal and then dress it up with nuts, dried fruit, or even marshmallows. Or buy junk cereal as one ingredient among many; just consider it equivalent to dried marshmallows. If you mix it, you control what goes into it. Here are some ideas for cereal mixes. Look for a store with a bulk aisle: these usually have several dry cereals and granolas, along with more fruits and nuts that you know what to do with. You'll also find healthy mix-ins such as bran and flax. You can make your own custom cereal here.
* Hardcore: make your own cereal from scratch. If you do this, you can capitalize on ingredients commercial cereals don't use, such as acorns. Here are instructions for making granola and muesli cereals.
* Here are some healthier cereals to consider:
In case you're curious, my standard lunch is Red Mill muesli in Old Country Style or Gluten-Free flavors. I add a small amount of quick oats to make it creamier.