Mark Rotenstreich has an unusual working life for a high-flying Manhattan lawyer. Not only does he choose which clients to work for, he also typically puts in a 40-hour week, has free weekends and takes vacations when he wants without fear of interruption.

“I work very hard but have much more control over my life than I would at a law firm,” he says. He works in an office in his apartment building or at the offices of his clients, which include The Economist Group, Virgin Mobile and A Small World, a social networking site.