I agree with MDtR-Chicago. During many weekends, the Bay Bridge westbound has been crowded even before noon, and its West end is near the start of the race course which could still be crowded with race participants/observers leaving.
Unless you have reliable traffic display software that shows the Bay Bridge Westbound to the City and Southbound 101 traffic moving well through the City, compared to the 880 Southbound flow (they don't call 880 the "Nasty Nimitz" freeway for nothing), I'd go with the 880 S. to the 92 West (San Mateo Bridge). From the 92/101 junction, it's only about 10 mins. North to SFO.