Not a cocktail, per se, but a great drink for the summertime. I made this recently at a party for my brother-in-law's wedding (thus the name) and it was a big hit.
Sangria del Matrimonio
750-ml Bottle of Dry White Wine
5 oz Grand Marnier
8 oz Pineapple Juice
12 oz Peach Soda or Nectar
Mix in a pitcher with sliced peaches and oranges. Strain into cups with ice to serve.