This is an interesting one, because despite having my own company and wanting feedback from my clients whenever there is a problem, in most cases when it comes to hotels I most usually just go vote with my feet and go elsewhere rather than bothering with a letter to the CEO.
This is not to say I don't complain when I am not happy about an experience in a hotel. I have had very poor experiences in the last six months at both the Four Seasons in Sydney and the Oberoi in Delhi. It is a question of priorities, but I would rather spend my time on other things apart from writing to the CEOs of Four Seasons and Oberoi. Often (but not always) the duty managers or the Front House Managers are helpful in resolving any issues.
The exception to this would be a travel provider you HAVE to use. This might apply in a city where there is no other reasonable alternative (eg Canberra in Australia or Agra in India). But if you have a bad experience at a luxury hotel where there are reasonable alternatives, due to time constraints I tend to vote with my feet and spend my money at their competitors.
This is the opposite to what I want my clients to do. When my clients have issues with staff or with service delivery, I want them to ring me. But then any management worth their salt will be looking for booking trends and identifying issues which may be contributing to those trends.