We don't like to give our littles much sugar, but we do find that offering them a "dessert" after dinner can be motivating. We have a "no sweets if you don't act sweet" policy, and it can be effective in helping with needed attitude adjustments.
Also, treats are just fun. And I like to bake. I've especially enjoyed baking with our kids lately.
This list of Low-Sugar Treat Recipes is worth looking at if you want to make some treats while avoiding too much sugar.
:)