“Basically I was looking for a hotel room,” says designer William Sofield of his recent move from a 5,000-square-foot loft in Manhattan’s East Village to his 750-square-foot parlor-floor rental in a Civil War-era brownstone just west of Fifth Avenue. Sofield — one of the busiest and most sought-after talents in his field lives most of the time in eastern Long Island, and has another place in Los Angeles, where Studio Sofield has a second base of operations.