In the bustling Ferry Building, the Wine Merchant is almost always busy. Judging by the crowds, even Saturday morning is not too early for a glass of wine when you're on vacation (we presume).
Sit at the wine bar and watch the crowds drift by. The wine list is always changing, and pours are available in 2 oz and 5 oz. (Or, of course, by the bottle.) They serve cheese and charcuterie from Cowgirl Creamery and Boccalone, whose stalls are just steps away.
Note that the wine bar closes at 8 p.m. most nights. This is a daytime drinking establishment!