transit
I live in Menlo Park and work in Sunnyvale, and I don't have a car. Not having a car is kind of ususual for the Peninsula (as opposed to pretty normal in San Francisco). I really enjoy it, though. I dislike driving, especially in traffic. It's stressful, expensive, and bad for the environment. I never liked it, even when I did it every day, and my time in Edinburgh spoiled me. So I take Caltrain, bus, or BART to go places a lot of the time. Lately I also cycle. It would be reasonable to call me a transit geek.
There are some great things about Bay Area transit. You can get most places on it. It's not outlandishly expensive: a monthly pass for Caltrain, SamTrans, or VTA can be as little as $45-60. You can take your bike on Caltrain, SamTrans, and VTA, and on BART during off-peak hours. But it does have its downsides -- if you're going to be a transit geek, you want to be prepared.
I use transit both for commuting and for general transit. Commuting is by far the easier of the two; general transit is more challenging. And sometimes cycling is the most challenging of all -- though also the most fun.