I'm flying into SFO for a 4 day stay; staying with a friend in Mill Valley. During my stay, I'll need to make two trips to UCSF. Then back to SFO for my departure. This visit is both person and professional, not really a sight seeing trip per se, though I hope to see a few things on my first visit to the area.
Given those distances, am I an exception to the standard advice that visitors don't need cars? My plan as it stands is to rent a car at SFO; best discounted rate I can find is $314 for the 4 days.