The Negroni is a classic. I like it with Punt e Mes vermouth but in this drink Martini & Rossi is fine (just make sure to use a fresh bottle, vermouth doesn't last forever once opened).

You can also mix up the amaro. Campari is an understandably polarizing ingredient. Try Leopold Brothers' Apertivo. It's far less cloying than Campari. Leopold Brothers also make a fantastic gin.

The Corpse Reviver #2 is possibly my favorite gin cocktail. Equal parts gin, orange liqueur, Lillet Blanc and lemon juice with a dash of absinthe.

If you want to try it, skip the Lillet and find a bottle of Cocchi Americano. The current formulation of Lillet Blanc is far sweeter than that of the 1930's. Cocchi Americano is a closer (and tastier) approximation.