I have found Aperol works as a sub for Campari in most cocktails in which Campari is a major player.

For something like a Jungle Bird, which uses Campari as subtle flavor component, I would just slightly reduce the amount for the Campari hater rather than sub.

This is one of my favorite cocktails but it MUST be balanced properly. Follow Difford's recipe!

I think they act on the flavor of the cocktail in a similar way to sweet vermouth, but in a fresher, more natural way.

Despite its somewhat less than auspicious origins, this is a good drink when well made, adhering to the specifications of the recipe. Don't free pour this one, no matter how much of a rush you are in. It's not sophisticated maybe, but it's fun and fruity. Float some raspberries or blackberries for a sweet finish. This is not a serious drink. It's something to have by the pool on a warm and sunny day.