Thank you for the link Kagehitokiri, and sorry for my poor abilities in searching old posts.
It seems so difficult to find THE place to stay in London. In Paris it is way much easier: George V is the best palace in the city far ahead its competitors.
We will be 6 adults, no children, no specific budget limitation, no specific area. We prefer a modern style suite but classic shall be fine. The only requirement is that I want a real 3-bedroom suite, no connecting rooms with a strange lay-out.