James McClain Forget this glassy Hollywood Hills mansion or that shiny new Bel Air palace, the hottest new Los Angeles mega-homes are “mansions in the sky,” condos in the swank residential skyscrapers popping up all over the city. With Manhattan-style services like 24/7 concierge and valet, room service and in-house restaurants, they provide amenities even the glitziest single-family homes can’t match.And suddenly, it’s not just one or two developments.