At the IC Marine Drive, there is a small pool of butlers who look after any requests and are the main contact points. It's nice if you stay a couple of times because the service from most is really friendly. It's not that the service is necessarily better than it would be otherwise, but it is nice to see familiar faces and know the person's service style.
At Chiva-Som in Thailand, butlers are assigned to the suites. The same person looks after you every day (excepting days off, of course!), and the service is very proactive. The butler would come to visit us in the suite at least once a day, and she would make sure she found us when we were outside the suite at least twice a day just to make sure we had what we needed and that everything was ok. Whenever we requested anything, she would deliver it. She was superb, and apparently impressed Mrs Mohammed Al Fayed sufficiently that she is now in her employ in London.