One of the finest and oldest cocktails around is the Manhattan cocktail, made with bourbon, sweet vermouth, and bitters. This classic cocktail is a must in any bartenders skill set. Lots of people say this classic should be always stirred, but it depends on how you like it.
Stirred looks classier and tastes a little more natural. Shaken gives it a bit of a chill and makes it look a bit cloudy which poured right can look very cool.