Given the weather, there’s seldom much call in New England for ceiling fans. Even so, the whirring hum beneath the Oak Bar’s carved mahogany ceiling adds a touch of airiness to a room that might otherwise seem stodgy. In fact, the Fairmont Copley Plaza’s bar strikes a perfect pitch between opulence and ease. The marble on the walls and generously apportioned martinis are the best kinds of throwbacks to a more civilized age. But the scene stays lively with the help of energetic jazz bands, a chatty and helpful staff, and a menu rife with inside jokes. The signature dirty martini, for example, is named after the Charles River, though we can’t imagine our current teetotaling governor diving into one anytime soon.