Bowe, 58, and Stewart, 51, a retired executive at JP Morgan, share a life goal of spending more time with friends and family, and this house, which they purchased a year ago, is an idyllic spot. Ironically, the thing that makes the home so perfect also made it a design challenge. Unlike many city homes that are long and narrow, the townhouse has a pleasant, wide floor plan. But its verticality is more like a lighthouse than a townhouse. And the constant, shifting light and shadow caused by the reflection of sunlight off the water was as key to the design as the walls and fixtures.