Or/And, if safe storage exists at both ends, bicycle with electric support, which should increase the no-sweat speed even further.
Electric and fold-up are both decent options. I rate them both above taking Muni and below just walking for myself. It still irks me that I can't just hop off a train at Embarcadero and onto a local BART train to somewhere closer to work. Once again, as in so many other situations, the last mile is the killer. :(
Maybe a Solowheel or equivalent for portability's sake. It would mean less exercise though.