thanx all for the replies.. let go back now to San Francisco...

i will stay in San Francisco for 4 days.. i have questions regarding transportation:

1- from Airport to Hotel? taxi or shuttle or.... ?
2- mostly i will be Staying in Union Square.. prices lower than fishermen's wharf.. what is the best way to transport, i was thinking of using double Decker bus? since it arrive in every location every 20/30 minutes? or am i wrong?