Where:
Philadelphia. It's fairly bike friendly. The roads suck outside of center city, but they're usually empty enough to get around the bad parts without being nailed. Drivers are nice, or at least tolerant. I've only had a few confrontations.
When:
I ride to school every day, rain, shine, hot or cold. I have never taken public transportation. It's either 2 or three miles, depending on which campus. I can do it in 7-10 minutes, respectively. It can be crowded, especially in morning rush hour, so I occasionally slip onto the sidewalk to get around tight jams.
I always do grocery shopping on the way home, so I've learned to get exactly what will fit in my messenger bag, no more no less. You can't hang paper bags off track drop bars, I've discovered. They catch in the spokes and explode.
I also ride recreationally on the bike path by the river. There's a great ten mile loop for quick steam off-blowing.
How:
Moderate to fast. When I'm in a hurry I blow more lights, of course, but I try to follow traffic laws as much as is reasonable. I ride fixed most of the time, usually at the speed of the traffic (slow city streets). I've seen too many people get hit to be reckless, though those duck bus thingies have these great tempting handles to skitch off and sometimes I can't resist.
First thing in the morning I'm usually barely alive, and the ride perks me up. Somehow my brain goes into autopilot and I can float through traffic, even though I'm so fogged sometimes that all I can say is 'Snnnnrg?'
Yeh, biking is my pleasure and salvation and probably my downfall (literally) one fine day.