With its 11-foot ceilings, trio of balconies and west Manhattan address, the penthouse triplex at 105 W. 89th Street is a spacious, functional oasis at the cluttered city center. Architects at Marble Fairbanks combined two townhouses for the $2.8 million condo, which was built for the founder of a large health-care company. The owner tasked the architects to create a home that could also serve both work functions and social events and be easily converted to accommodate out-of-town business guests. The three-story, 2,450 square-foot condo has a 600 square-foot rooftop terrace, four bedrooms, a large atrium skylight, a pair of wood burning fireplaces, electronic window shades and a home theater and has won awards from the AIA and has been featured in several design publications. [realtor]