I agree wholeheartedly with other comments on the FS George V. It is my favourite hotel in Paris.
My first post was just comparing the physical attributes of the Pen with the Plaza Athenee. I personally prefer Le Cinq (and Phillipe Legendre) to Ducasse -- I always have troubles trying to justify the Ducasse "premium"; and I think the staff are more personable.
The Concierge team (I have raved about them in previous posts) are, in my mind, the best, under Roderick Levejac, Chef Concierge and Secretary of Les Clefs D'Or International. His former Assistant, Jean-Jacque Yonnet, is currently the Chef Concierge at the Four Seasons Provence.
It certainly isn't cheap to stay at the George V; but one doesn't mind. I would NEVER spend over £400 on a room in London............. no way!!