I live in LA and I have to drive to work because there's just not simply a viable alternative to where I have to commute to (West Adams area to West Hollywood.) The bike lanes across LA are spotty at best and there's a good chance you're going to get hit/brushed by a car because the closer you get to Beverly Hills/West Hollywood, the more impatient/asshole-ish drivers become.
LA is trying to solve this right now with better public transportation, but even then the line that runs into Beverly Hills/West Hollywood requires me to take I think a train and a bus before I can even get to it (also it's not complete for another 4 years, I think.)