Outdoor kitchens are my favorite element! So versatile, functional, and will completely enhance any outdoor living space. If you are looking for that "wow" feature, kitchens are they way to go.
Be careful about assuming their ability to be phased into your project. With electrical and gas, typically needed for your appliances, holding off on the kitchen might not be the best idea.
I suggest knowing what all you want to incorporate into the kitchen before you try to plan the look, type of material, and size (are the appliances, gas, electrical, or propane).