I've been commuting (and riding for fun) since ~1992. Since then I've owned 34 cars/motorcycles (which I drove the absolute heck out of), but I stopped driving in 2003. Seems I have a crazy lead foot which works out great for biking and gets me in lots of trouble for driving.
Living somewhere with a nice public transportation system is definitely a plus. I lived out in the country for a while and have to admit I grew weary having a 45 min commute just to get into the city limits each day.
No way I'd go back to driving now. Biking is too much fun. Sure I spend a lot of money buying new bikes or new parts, but nowhere near the amount I spent customizing my cars or paying insurance each month!