Traditional a black and tan is either a stout or porter, then mixed with an English style Pale Ale. However, thats just tradition and you could do whatever you want! Brewing is all about doing your own thing.
A Vienna lager does sound interesting with a stout. Nice mix of sweet and the dry/roasty flavors
Primary1: Pumpkin Ale
Primary2: Christmas Ale
Secondary: Sour Brown
Drinking: Warrior Pale Ale, Wit, American Rye