Oprah Winfrey's 4,607-square-foot Chicago co-op apartment in a 1913 Beaux Arts building is now available to rent for $ 15,000 a month. What exactly does $ 15,000 in rent fetch these days on Lake Shore Drive? Views of Lake Michigan, from the library and master bedroom, for one thing.For another, that master bedroom is a whopping 1,200 square feet in size, and includes a his-and-her bath. There