Here's another drink that you can order without looking like you (a) don't know what you're doing (anything with the word "seven" in it), (b) are 17 years old (Jaeger), or (c) aren't the sort of manly gent your grandpa would have respected (things with umbrellas in them). The first of my occasional series was the Manhattan, which you can read here.
The Negroni can somehow be both refreshing on a hot day and warming on a cold night. And it's easy to make even if you've already had five of them. The classic is one part gin, one part sweet vermouth, and one part Campari, served on the rocks (please stir before enjoying) with a twist of either lemon or orange peel. I like to twist this a bit: more like one and a half parts gin and half a part of Campari, because frankly a little bit of exceptionally bitter liqueur goes a long way. This works particularly well if you use a highly aromatic gin.
My favorite variation of the Negroni, unsurprisingly, is to simply make it with bourbon rather than gin, which is called a Boulevardier. The only downside whatsoever is that saying "Boulevardier" is difficult when you've been drinking. People make variations of the Negroni using other liqueurs or bitters than Campari, but if you're making a traditional, bitter drink with something sweet, are you really making the traditional, bitter drink at all? Thus, the only acceptable substitutes, as far as I'm concerned, are also bitter, herbal or vegetal concoctions like something made with Cynar (artichoke liqueur), Punt e Mes rather than whatever sweet vermouth you've had sitting open in your fridge for the last six months, or by subtly altering the herbal flavors with a dash or two of a favorite bitters. Celery, orange, or cardamom bitters would all be good choices here.
Part 3 will appear whenever I next feel thirsty this afternoon.