add wood wallpaper to the kick plates of the stairs. Those rolls are expensive but you would only need one. Not practical with white treads though, it will be stuffed up from black shoe soles in no time.
This is a very well rounded coastal color palette. Can you see this in your home? Keep the lighter colors for your foyer, darker colors for accents or dining room, restful greens for the bedroom and those spa blues for your bathroom.