Katherine Schlosstein is decisive. When she came to the initial meeting with her architect and designer about the renovation of her Manhattan duplex , Schlosstein didn’t just arrive with general ideas —she showed up with a presentation. “I had a Powerpoint ready, yes,” she says with a laugh. “I know what I like and don’t like, but I'm not overly particular. And because we’re all friends, I wanted to make the process seamless.” A Pierre Augustin Rose sofa and coffee table in the living room overlook a custom Moleanos Limestone mantel and a custom mirror. The pair of Pierre Jeanneret chairs are from 1stDibs . Noguchi Akari 45A Ceiling Lamps West Elm Flynn Dining Chair Schlosstein is no stranger to a Powerpoint. As a born-and-raised New Yorker, she works as the vice president of marketing and communications for Loro Piana . After a long stint downtown , she decided to take her mom’s advice and tour listings that would root her near family on the Upper East Side .…