I ended up with a 2L of Deep Eddy Grapefruit vodka. A year later, still have about 2L and want to leverage it for Thanksgiving in a punch or sangria, something that will use a lot of grapefruit vodka. Thinking about cranberry and rosemary maybe, I have many liqueurs and time enough to get any mixer.
You can rim the glass with salt and garnish with lime, serve over ice!
You can also add various chopped fruits or other juices for a nice visual/taste mixup, like that cranberry.
Keeping it simple! The Deep Eddy one is probably nice enough to do this with. I am considering mezcal but it's sort of divisive in my Thanksgiving crowd.
If you just want to use it, I'd turn it into modified Paloma's. Mix up grapefruit juice, grapefruit vodka, rosemary infused vodka, and some Angostura bitters in a pitcher and refrigerate. Then to serve, pour the mix into a highball with ice and top with a little grapefruit soda (I strongly prefer San Pellegrino), garnish with a small sprig of rosemary. You might add some sweetener or something to tone it down. You can also make it a little showy by smashing the rosemary sprig with a big flourish and handclap.
I left off portions since I really don't know what the vodka tastes like. I'd sample it first with mostly vodka and then up the other measures as needed to get something palatable.
I love that vodka with a squeeze of lime and just soda water over some ice. Everyone I've had try it seems to like it. It is, however, more of a summer/warm weather drink.
Grapefruit is one of my favorite flavors, next to cranberry, and if you want to do a pitcher type drink, an easy thing might be a grapefruit Screwdriver (a nice OJ, or even with blood orange juice and the grapefruit vodka).
Jumping off the Screwdriver base, it would definitely support a hefty amount or even just a splash of cranberry juice (if you want intensity without dilution of added sweetness, I recommend Knudsen Just Cranberry for highly concentrated flavor), and plain or burnished fresh rosemary sprigs, a squeeze of lime and a wedge of lime, or orange, ahh, it's endless! You could give it a fizz with soda water or flavored Italian soda, anything that slides into the profile, make it more holiday with a cinnamon stick, or stronger and more complex with botanicals of some gin, yadda yadda, I'm not helping! Too many options, I'm getting envious of your quandary.
A Grayhound, just also use the grapefruit vodka, similarly with Salty Dogs. I'd go so far to recommended Tanqueray Rangpur Lime Gin, for that added citrus with the botanicals, but I'm big on flavor, and that'll get expensive pretty quickly in quantity. Fresh lime juice goes a long way.
You could also just get a bunch of cheap regular and diet tonic, (for options) and make up pitchers or pretty carafes of V & Ts. It's nice enough flavor wise on it's own, but great with all the above flavor options, too!
Regardless, you probably can't go wrong with Deep Eddy, and a singular something tasty to mix.