If I worked near or in Pioneer Square Zeitgeist Coffee would be my normal coffee store. It's a great space. It pours good coffee. Service is really friendly. Pastry is good (I'm told - I didn't indulge). Wireless is free.
The store is huge so there doesn't seem to be any problem finding a chair. And it's consistently busy, even though it's located less than a block from Starbucks. It was an eclectic crowd, from construction workers to Amtrak workers, software startup guys to people in suits. I was there for over an hour and I never saw the line get shorter than 3 deep.
If you're around Pioneer Square and you crave a caffiene hit, seek this place out.