What makes a good charter yacht?

Having just been to the Monaco show and been on a broad variety of yachts, some clearly designed for a specific client, but most with a view to resale or charter; I began to wonder what are the essential features of a 50m plus megayacht to be designed for charter. Should the yacht appear very neutral in styling and function, should their be an emphasis on public spaces, what are the crew implications etc. Any suggestions?