Traditionally made with rye whiskey, the Manhattan is often served with bourbon today. Either works well in its own way and rye has enjoyed a resurgence in recent years. There are three key variations on the mix, and you will likely be asked for your preference when ordering a Manhattan at a reputable bar: dry, perfect and sweet.
[short excerpt from Cocktails of the Movies]
2 oz / 50 ml bourbon or rye whiskey
1 oz / 25 ml sweet vermouth
2 dashes Angostura bitters