Concierge.com's insider take:

Dukes is tucked away down a cobbled cul-de-sac, a stone's throw from Prince Charles's official London residence, Clarence House, where Princes William and Harry bed down when they're in town. You'll be seduced by this place as soon as you see its pretty doorway and cool, calm interior—it's like entering a grand old library, all hush but without the stuffiness. The Dining Room (serving traditional dishes such as guinea fowl and beet terrine), Drawing Room, and Dukes Bar have understated, classic decor, with Queen Anne chairs, rich wallpaper, luxurious soft furnishings, and oil paintings. Bedrooms come in silvery grays, blues, and greens, and the suites have spacious living rooms with plush sofas and majestic dining tables fit for high-class dinner parties or high-powered business meetings. The rooms were modernized in 2007, so now there's Wi-Fi and iPod speakers alongside the stately decor. The best room, of course, is the Penthouse Suite, with its private balcony overlooking Green Park. Down in Dukes Bar, the signature cocktail is the classic martini, prepared like a sacred ritual table-side with a crystal atomizer.