Not starbucks, but I use a local coffee shop as my 'office' on days I don't want to work from home. It's quiet, free internet, and coffee on tapIn fact there are a few other people I see in there regularly who do the same thing.
You're right about Starbucks though. No way I could spend more than 5 minutes in that place. I don't like the culture, the people who work there bug me and the 'let me see how many words I can have in my coffee order' people bug me too.
You know what bugs me, people who think that starbucks has a culture and that ordering a drink you like that happens to be longer than 'black' is something looked down upon. It's too bad everyone can't be as cool as you dude.