I have about seven bottles of cocktail bitters on my bar cart, but I really only use two—Angostura and orange—when making cocktails. It’s not that the other flavors are bad, it’s just that I rarely want an old fashioned made with grapefruit or lavender bitters. But a lemonade is an entirely different story.
Source: LifeHacker – Make Better Lemonade With Cocktail Bitters