Has less calories and carbs than Bud, Sam Adams, Miller, PBR, Coors, and Stella! Guinness just doesn't market itself like that because it tastes so much richer than most lagers people are used to. (although I prefer Sam Adams over Guinness, stouts aren't my cup of tea)
For a Black and Yellow I'd say get a Guinness spoon and layer Guinness over Summer Shandy or Boulevard Wheat. One summer I got really good at this. So much when I bought a buddy a spoon and a mix and match as a house warming present he had me making him half and halfs (halves?) all night instead of trying it himself.