This town is to flea markets what New York is to bagels. If there's an antique you're looking for here and you can't find it it doesn't exist. It's not where I would go for a bargain but I'd sure go there for inspiration!
Take the Ferry between Ferry Building downtown and Sausalito. In Sausaltio you have Le Garage, Sushi Ran, Heath Ceramics. In Ferry Building there are ton of great restaurants and artisanal food stalls (meats, cheeses, breads, coffee, etc)
this is a MUST DO if you're a shopper-- it's opened on the weekends only and it's advised that you get there super early. It's HUGE so allow a full day to get there are shop around. Great for basically anything and everything from handcrafted items, furniture, food, etc.