In a large pitcher, combine syrup, lime juice, grapefruit juice, and tequila.
Chill in the fridge until ready to serve.
When ready to pour, rim glasses with salt and fill with ice.
Fill each glass about two-thirds full with the Paloma mix.
Top with grapefruit soda or club soda and garnish as desired (grapefruit wedge, lime wheel, or dried citrus).