Tartine is one of my absolute favorite bakeries and a must every time I'm in San Francisco. I actually am a little bit worried about what might happen once I move up there... I fear it could be habit-forming.
Their bread is incredible, as are their sandwiches, desserts... pretty much everything. It's a bakery, cafe, and even wine bar, and I love the vibe that comes from people opening up a bottle of white at lunch on a Saturday. With the line almost always out the door, there's always a ton of energy, great people watching, and a cool European cafe-meets-San-Francisco,-specifically-the-Mission,-vibe.
Check out this video to see the owner and head baker, Chad Robertson, in his element. Although I'll warn you, this is dangerous to watch if you're hungry.