When I am in a cocktail mood, it is usually a 19th-century Martini a la Rombauer: 1 part dry vermouth, 1 part sweet vermouth, 6 parts gin, dash of orange bitters, olive, ice. But my usual nightcap is plain anisette on ice. If the hot weather ever comes back (for the time being it is high in the 50s F, day after day), I'll vary that with gin & tonic.