I loved staying at 44 Curzon Street by Mansley. Perfect location and an extremely attractive, well laid out flat. There were a few mysteries in the kitchen (like flatware in an ingenious drawer below the cooktop) which were quickly cleared up by the very helpful and always friendly concierge, Paul. Being able to make breakfast in the flat was a big plus in my book. Several groceries are near by. As far as transportation is concerned, the Green Park tube is only a few blocks away, located in Green Park which is lovely for strolling. Buckingham Palace is a short walk away, as are are the Ritz and Harrods.
All in all, 44 Curzon is the perfect home away from home while in London. I will definitely book again.