Want to make this for a group? To serve 8, use 2 cups vodka, 2 cups grapefruit juice, 1/2 cup simple syrup, 4 cups rosé (this is about 1 1/2 bottles - a little under), about 1 cup club soda. Stir together the vodka, grapefruit juice, simple syrup and rosé in a big pitcher and chill it well before serving. Pour into glasses and top with the club soda!