Personally, nothing beats the Grey Goose Limon Marti in France.
Those things could get a girl into trouble..they do NOT taste like there is any alcohol in them whatsoever. I could drink them ALL day long.
But there are some other great "grown-up" drinks at Disney that I must have..the Strawberry Margarita at OKW...the Glowtini (do they still have that??)..a Strongbow from the UK (not exactly a cocktail..) and a Margarita from Mexico..although I am convinced that if someone lighted a match to close to my mouth after I drank one of those that I could breathe fire (because they are STRONG!!)