After searching high and low, I've finally found a neighborhood coffeeshop that combines all the elements I'm looking for: The coffee is good. The decor is somewhat upscale (granite countertops) and clean. There are plenty of high-back easy chairs and bistro tables, indoors and out. And the staff never sends even the remotest twinge of attitude if you spend hours in there and only buy one drink. This is a neighborhood coffeeshop in Russian Hill, on Polk St. Lots of students and quirky eccentrics. Only drawback with writing a review like this is that it might become even more crowded than it already is (sometimes you have to wait or share table with stranger to find a seat).
Pros: great staff, good coffee, easy-going pleasant ambience