As far as commuting goes, I walk whenever I can get to where I'm going in 30 minutes or less, bike when it's going to be 3-10 km and drive the rest. I'm a very defensive ped, doing double-checks and making sure I'm safe when crossing streets and such. My wife [in my view] just wanders out into traffic, assuming that all vehicles can and will stop. She seems to have an invisible bubble around her that protects her from harm.
When biking, we're the opposite. I whip through traffic with my spider-sense warning me of danger, while she tends to take it a lot easier. It's weird that we have such a different way of behaving on and off the bike.