The Beacon, high on the second floor of a waterfront building, gives no sign from the road that it has a great view of the boats in Sag Harbor Cove, North Haven, and the setting sun. Beacon doesn’t take reservations, so you can’t be sure of getting a coveted table outdoors. But even indoors, you can share the view. The kitchen pays attention to detail. Roast chicken comes with carrots and shallots and smoked bacon-pecorino risotto. Steamed mussels have a creamy-tomato sauce. And bouillabaisse, with mussels, clams, lobster, and grilled scallops and shrimp in a tomato, fennel, and saffron broth, has become a favorite.