In designing a weekend house for a couple from Manhattan, Ryall Sheridan Architects in New York first helped locate its site on the North Fork of Long Island. Bill Ryall, firm principal, who has built up a substantive portfolio of quietly modern residences in the area, found a 5.5-acre plot in Orient, a quaint rural village of 700 people. The flat property ends on a high bluff overlooking the Long Island Sound. Here, at its northern edge, Ryall placed the T-shaped, 5,660-square-foot wood structure and elevated its living spaces, piano nobile fashion, to take advantage of the dramatic view.