Aside from the sofa, the living room in Peggy Gou's Seoul-based apartment embraces relatively minimalist decor. The colors are neutral, and the furnishing is sparse, but impactful.

Kelsey is currently designing a client's early 1900s home in Rye, New York, and they used her own dining room as a jumping-off point. "They saw this room and loved it," she says. "It's cool to think ...