Rivoire
One of the best spots in Florence for people-watching offers stellar service, light snacks, and terrific aperitivi. It's been around since the 1860s, and has been famous for its hot and cold chocolate (with or without cream) for more than a century. Though the food is mostly good (it's not a bad place for a light, but expensive, lunch), it's best to stick to drinks (both alcoholic and non-) and the terrific cakes, pies, and pastries.