Margarita (1 L)
This is a shameless rip from Mr. Regan’s recipe, but it is 1.5 times the volume.
12 oz white tequila (preferably 100% agave; Cuervo actually makes a decent one, the Tradicionale)
9 oz Cointreau (or triple sec, but I only bother keeping the former around)
4.5 oz lime juice
7.5 oz filtered / bottled water

Fish House Punch (1 L)
There are various, relatively divergent, recipes for this out there in the world, and this is cobbled together from several. Apologies for the ⅓ measures: it took that to hit the right balance in 1 L. Obviously, I just eyeball it between ¼s.
500 mL dark rum (I use Gosling’s)
6 oz brandy (not really worth using cognac or armagnac here)
2⅔ oz peach brandy or crème de pêche
2⅔ oz simple syrup
3⅓ oz fresh lime juice
3⅓ oz fresh lemon juice
fill with filtered / bottled water (if there’s any space left)

Bottled Stiles (1 L)
This isn’t enormously clever, but it is something that I came up with when I first had a bottle of St-Germain. (It’s named for a street on which I’ve lived.)
300 mL gin (I use either Plymouth or Bluecoat usually)
150 mL St-Germain Elderflower Liqueur
150 mL Lillet Blonde
fill to 1 L with filtered / bottled water