The best thing I ate in San Francisco during GDC was the bone marrow at Two. Bone marrow is a lot like butter-collards, it can be disgusting if it's too plain, because it is basically pure fat, and it does have a slightly weird vitamin-like bone taste. It's been trendy to cut it with a bit of persillade or gremolata or something like that, but at Two they serve it in a kind of reduced-broth onion gravy, which was perfect. It enhances the meatiness and tames the vomit factor, and provides some extra nice tasty bread dip.
(the Raviolo at Two was also excellent - a soft cooked egg yolk in a pasta wrapper with brown butter sauce, very simple but delicious. It would've been better with some crunchy pancetta bits sprinkled on top. That also continues a trend I've seen a lot recently of really interesting and well made delicious appetizers, leading up to rather boring and lazily made main courses.)