Originally Posted by squeakr

except for Chinatown, a car would be a help. Although parking is expensive anywhere in SF and complicated - many "no parking ffom 4-6 PM" etc. , to get to Ghirardelli and Pier 39 and Lombard St in one day from SFO you would likely need a car.
BART to SF will be $8+ each so $32 for each way - so a car will also be cheaper.
TO visit Chinatown you'd best park at the Sutter-Stockton Garage and walk around

Others who drive more in SF may have better advice re the parking lots and charges.