Vesper: I love me a Vesper, and not just because it's named after the babeliest Bond girl of all time. This derivative is delicate and floral, equal parts gin (I go with a rounded, botanical-heavy style like FEW or Monkey 47) and vodka, a fragrant French aperitif called Lillet Blanc, finished with a lemon twist.
Turf cocktail: This semi-obscure take packs a potent punch with gin, dry vermouth, a quarter ounce of maraschino liqueur, a dash of absinthe, orange bitters, and a lemon twist.
Upside-down martini: A bizarre, low-proof sipper, it's essentially just a martini with an inverted spirit-to-vermouth ratio (i.e., mostly vermouth). Legend is Julia Child got loose with this one on the regular.
Bitter martini: Italian amaro (no vermouth) and a fresh grapefruit twist are the bitter culprits behind this bold, citrusy variation.