The Thousandth Floor, by Katharine McGee

A hundred years in the future, New York neighborhoods spread up, not out, and the center of the city is the Tower, a thousand-story skyscraper that encompasses all walks of life. On the very top floor in the penthouse lives Avery Fuller, genetically engineered to be perfect. In the Tower, the further downTower you go, the cheaper and less desirable the real estate, so as denizens of the highest floors, Avery and her friends lead glittering lives as the upper-most echelon of New York society and wealth. But each hides a secret -- a drug addiction, a forbidden love, a long-buried betrayal -- and more than one of them is doomed to a very long trip down, both figuratively and literally.  The Thousandth Floor is an entertaining mix of sci-fi (transportation, energy and communication in the future is as innovative as you might expect) and froth. Just as a book like The Luxe reads like Gossip Girl set in the past, The Thousandth Floor reads like Gossip Girl or Pretty Little Liars set in the future. Lots of intrigue, romance and teens behaving badly, but lots of fun to read!