A negroni is equal parts Campari, Vermouth and Gin. Varying the brand of Vermouth or Gin has the biggest impact. Subbing out Campari makes it another cocktail. Should be swapped out for another Amaro (Herbally Bitter Liquer) such as Cynar, Gran Clasico or Brut Americano (never Aperol, too sweet). I'm partial to using Cynar (pronounced chee-nahr) which I've heard be called a Sin-Cyn (sin-chin).

You can also try swapping the gin for whiskey to make a boulvadier and see if that more to your liking as well.