I keep my bike in my office, so I don't need to worry about locking it up anywhere. However, if I couldn't keep my bike in my office or had to run a lot of errands around town on it, I probably would have more of a beater bike. I keep a small cable lock in my seatbag for special situations where I might need to lock it up, but that is rare.
On the other hand, I find that I do a lot less "traveling around" on days when I ride by bike vs. my truck. It's too much trouble to go out to lunch, or the bank, or a shopping center on days when I bike commute. So I do those things when I drive. That's part of the reason why bike commuting helps cut down driving so much -- because you save not just the commuting distance but all the mileage you would rack up driving around during lunch and after work.