They carry seltzers (although I'm not sure if they're like High Noon which is vodka based or what), light beers like Michelob with low carbs, and of course you can always do two-ingredient drinks with zero carb mixers like Jack and Diet, Vodka Soda, 7 & Starry Zero, etc.
Ordering a Vodka Soda and squirting a little Mio in it is a neat idea. I like Jack and Diet a lot, that's my normal drink anywhere, so that's what I usually order.