A few years ago, Eric Birnbaum, a partner at Imperial Companies, was enjoying a drink at the buzzing lobby bar of the Bowery Hotel when he was struck by a question: Why couldn’t the lobby of a residential building have just as much energy as a happening boutique hotel? “In the residential space,” Mr. Birnbaum said, “there’s been a real lack of creativity and ingenuity. It’s very staid and institutional, very cookie cutter. We said, ‘Let’s create a liveliness and a place that you really want to be in our common areas.’ The key to that is good food and beverage, good music and high design.” Henry Hall, the Imperial Companies’ new 225-unit rental building at 515 West 38th Street, is Mr. Birnbaum’s attempt to deliver just such a hot spot — a building that will blend the public and private in a lobby that is essentially a full-service lounge open to anyone, rather than a glorified hallway for building residents only. To realize his vision, he tapped Ken Fulk, an interior designer with a flair for glamour and whimsy; Delicious Hospitality Group, the company behind the Manhattan restaurants Charlie Bird and Pasquale Jones; and BKSK Architects.