The hubbub of big city coffeehouses is indeed not conducive to hacking. If you have the luxury of being able to move around, it's worth checking out coffeehouses in small towns. My current favorite in Northern California is the Curly Wolf in Nevada City. Exquisite interior decoration, great people, quiet atmosphere, open til midnight Sun through Thu, til 2am Friday and Saturday. And if you're willing to travel farther, you can even still find hacker's paradise, like the Shot in the Dark in Tucson, AZ: open 24/7. Trust me, it's quiet in there at 3am.