The Chelsea Market is filled with great restaurants and speciality food stores and pop up shops. I love stopping in and getting a gourmet grilled cheese from Lucy's Whey or a healthy juice from raw food restaurant One Lucky Duck, while shopping for dinner ingredients at the Italian market Buon Italia. For a great sit down restaurant, I love The Green Table, which serves great farm to table food.
You've heard about the reading room at the New York Public Library, haven't you? Then I need not go on. Just look at it. And you're allowed to hang around in there!