Lever House, a landmark midcentury skyscraper on Manhattan’s corporate headquarters-heavy Park Avenue, is undergoing a major overhaul for the first time in 70 years that will feature an exclusive lounge, restaurant, conference venue and hospitality suite with outdoor terrace space on its third floor. The design is the latest example of a high-profile U.S. building doubling down on amenities that aim to attract tenants and make going to the workplace a more desirable experience.