I love Jeanne's suggestion. There's tons of wonderful dogs at shelters, and big ones often have a harder time getting adopted because of their size.
Far as specific breeds go....I would suggest a Dane, or a Mastiff. (big, short hair and very mellow) There's others, too that I like, but their energy level is pretty high. American Bulldogs, Boxers...both pretty energetic. Have you considered rescuing a Greyhound? They're large, have short hair, and are very very mellow in the house. They are highly recommended for apartments cuz they're basically big couch potatoes.
Rotties, Dobies. Big and short hair..can both be kind of energetic, though.
Bloodhound? Big, short hair...but really need to be looked after and not let out off -leash in an unfenced area.
Hmm...out of ideas for the moment.
OH! How about a Greater Swiss Mountain Dog? They're large and have short hair. I'm not too familiar with their energy level, though.