Kitchen cabinet molding comes in many different sizes and types. Much of the sizing is a matter of taste and the look that you want to achieve. Do not install so much crown molding on your cabinets that they have a top-heavy look.
Purchase cabinets that reach the ceiling or nearly reach the ceiling, and buy the molding in the correct width to fill in the gap. A good rule of thumb when applying moldings is the higher the ceiling, the wider size of molding you can use to create a good look.