The Frank Stella's are the best. They are all over the city and they always look amazing. Two of my favorites are the Saatchi and Saatchi lobby (pictured) and the Citi Corp building in Midtown.
German Expressionism makes me giddy. All my favorites are here at any given time - George Grosz, Otto Dix, Egon Schiele, Gustave Klimt - and the building was designed Carrére and Hastings, the same architects that designed the New York Public Library.
One of my lunch favorites - start with the crab toast lemon aioli, then roast carrot avocado salad, Kasha and Bowtie pasta with Meatballs - and their homemade sodas and green juice are awesome!
Has no sign outside, so you might miss it, but if you do happen to find it, you will feel like you have walked into the 1920's. Its very chic, with Black and white marble decor, candle light and ambience to go with a great list of cocktails and whiskeys etc.