To me, one mark of a great cocktail is that you almost can't identify the ingredients because it is so much its own thing. A cocktail can be good without that quality, but it's fun when you find it.
Noilly Pratt is my usual vermouth. About all I use it for is manhattans. I like Punt e Mes for a change of pace, but now I have two vermouths I rarely use. What else to do with them?
Recently I saw A. J. Rathbun's Punt e Mes highball. It's one part Punt and two parts ginger ale on the rocks. (I used Vernor's.) The drink is pretty great. Only two ingredients and it doesn't taste like either one of them. I'll have to try it with the Noilly.