The San Francisco bakery and patisserie scene is competitive and sophisticated. A rather new entrant is the b. patisserie that shows off a German/French baking style, mixed with a set of American ingredients and favorites.
If you have 'warmed up' in the 20-30 minute outside line during the weekend morning rush, your saliva will be running wild when you get inside and see the enormous display of bakery items. The founders are both pastry chefs and you can see that in the perfect presentation of bakery items.
My personal favorites include the Orange/Hazelnut Almond Croissant and the various scones.
One word of warning: the high expectations that build up during the wait and through the delicious presentation can't be met in taste. The taste is good, but I felt that several items are too sweet and do not resemble the presentation as perfectly. Many customers go on pastry binges anyways after the exhausting wait and are incentivised by the delicious smells.
Clear winners in terms of taste are the baked grilled sandwiches (incl. my favorite, the Flammenküche).
After you have been able to select and pay, you then face the next challenge – finding a seat is almost as hard as finding free parking in San Francisco (yes, the parking meters run Sundays as well here).
It also isn't cheap – pay as much as you'd expect at Tartine, but I feel it is not as sophisticated. It is as crowded during the morning hours. This is a great place to try if you are in that part of town, but I would not add it as a SF 'Must-Do'.