I have to admit I don't really get vodka. I have some good potato vodka in my drink cabinet, you can tell it apart from grain vodka by mouthfeel but generally I go for a low end triple or more filtered brand. It doesn't see a lot of cocktail action, getting used when fresh grapefruit is available in the salty dog. In high summer in cucumber Martinis or in Vespers.
One thing that vodka is good for though is creating cordials or liqueurs.
Do yourself a favour though & use reasonable ingredients.
1st Vanilla vodka.
1 Bottle of Smirnoff red or similar quality vodka
1 Vanilla pod.
Drop the pod in the bottle, let it sit for a couple of days and remove the pod. Don't leave it to long or the flavour will become bitter.
2 Generic fruit vodka
The trick with fruit vodka is balancing the sweetness, most soft fruits are quite acid and the result of just fruit is sometimes to dry to drink, so add a little sugar, if it's still too dry add a little more.
I'm currently trying a ginger vodka to replace Jamaica Ginger, I'll let you know how it goes and what drinks it ends up in.