To bus to my office, I have a 30 minute bus ride on one of the rapidride busses, then transfer to a king county metro bus. The second bus takes between 0 and 30 minutes to arrive, normally gets stuck in traffic on the route it takes, and arrives near my office in 10 to 30 minutes. This is assuming neither bus is full and picks people up at either stop.
On the best day, I'm on a bus for 40 minutes. On the worst, 90. That's 1.5-3 hours a day dealing with a commute.
Alternatively, if I drive, I leave when I want to and normally arrive in 15-20 minutes. On a good day I save an hour a day driving, and on a bad one almost 2 hours.
I'm all for public transit, when it works efficiently. We currently do not have a rail system that reaches the majority of our population (its being planned though). I can't justify the additional time for my commute, because I'd always have to plan for the worst.
The bright side is sound transit is working on a proposal to expand their existing light rail. I'm all for efficient, timely, and reliable public transportation. I live 4 miles from work. It shouldn't take up to 90 minutes for me to get there.