As the gravel and cobble driveway meanders toward Long Island Sound, it engages in a game of peek-a-boo, revealing, through leafy interludes, a dormer here, a red-brick chimney there, until it presents a stately Colonial-style home. The three-story, 18,000-sq.ft. white-clapboard house in Westport, CT, is an architectural ode to classic American style and was designed as a summer/weekend residence for a Manhattan couple whose five children of high school to college age are avid athletes.