Style by Emily Henderson has some fun ideas about what you can do with the space above your upper cabinets.

One thing we do not recommend: taking your uppers all the way to the ceiling. One problem that can occur: if the ceiling is not perfect, cabinet doors can actually rub on the ceiling. A small gap is a better solution. Ceiling fills are an option but come with downsides as well. We think the best option is to leave some space and do something creative with it.