I am not a vodka person. I prefer the very good variations of barley pop.

I like getting a neutral vodka (trader joes or costcos cheap house brands work perfectly) and soak fruit (cherries, blackberrys, and raspberries work well) in it for about 3 weeks.

I don't drink vodka, but I believe Grey Goose was one of my former mother-in-law's favorites (she being Mrs. Got-rocks), but here are some good options: [thespruceeats.com]

I Skyy vodka and chocolate liquor makes a pretty good chocolate martini, and made for a heck of a memorable family reunion one year.

I usually buy Smirnoff because it's traditional here. It's probably a less than adventurous choice but might suit your guest. I always put Coke in it.

Keitel one is good.

Does she prefer sour or sweet?