Muni also has a fleet of - not buses - but light rail trains. These trains, designed by Ferrari, travel on the surface away from the city center, and then go underground to become subways down town traveling very quickly without traffic interference. From my location (Cole Valley - just above the Upper Haight) a bus ride takes about 45 minutes to get to SOMA, and the light-rail about 25 minutes. So, if you can find a place on any Muni line, you will dramatically improve your transit times PLUS you won't have to deal with the crazies - they mainly ride by bus for some reason. The way you can differentiate a Muni light-rail from a bus line is the light-rail lines are designated with a letter, and the buses with a number. Avoid buses - life is too short - go light-rail.
And as ced pointed out, Cycling! For me, its under 20 minutes to ride to SOMA - cycling is one of the fastest ways to get around town, and the cyclists have become a political force here and have been granted a bike lane network in the city. But being right on a Muni light-rail line is perfect for those occasional rainy days.