In most cases when it's raining I just accept the fact that I'm going to get wet. I have a jacket/shell that breathes well enough but unless the temp is below 40°F I sweat too much in it so get soaked anyway. I mainly just wear clothing that wicks moisture and dries quickly so that I have something warm (when it's cold) and dry to wear on my commute home.

I would think that adding a bus ride in the middle of the commute would really complicate things but if it had to be done I would buy a good Gore-Tex type rain suit and commute on the bike at a leisurely pace so as not to sweat.