From SFO, you can take any BART train toward San Francisco and off board at Powell Street Station (http://www.flysfo.com/to-from/public-transit). It is a 10 minute walk from the Powell BART Station to the Grand Hyatt Hotel.
You can also easily access and utilize the various MUNI bus lines as well as BART trains to visit local destinations throughout San Francisco. Plan your local trips by utilizing the following websites:
For BART: www.bart.gov
For MUNI: http://www.sfmta.com/getting-around/transit/schedules-trip-planners
There are also Super Shuttle (http://www.flysfo.com/to-from/sf/shared-ride-vans), and Taxi (http://www.flysfo.com/to-from/sf/taxis) services available at the airport.
Transportation Options from SFO to Downtown San Francisco
BART operates rapid rail service directly between SFO and San Francisco. The SFO BART Station is located on the Departures/Ticketing Level of the International Terminal (Boarding Area G side). BART is easily accessed from any terminal by riding SFO's AirTrain to the Garage G/BART Station stop.
From SFO Airport to Powell Street Station (fare for one way: $8.65)
1) Take any train going towards the East Bay (Dublin Pleasanton, Richmond, Fremont, Pittsburg/Bay Point).
2) 10 Stops. Off board at Powell Street Station
From Powell Street Station to Grand Hyatt (walking. 0.4 miles. 8 minutes)
1) Exit via Powell Street
2) Head north on Powell street towards Geary Blvd. (walk for about 3 blocks)
3) Turn right onto Geary (walk for one block)
4) Turn left onto Stockton (walk for one block)
Taxis: Taxis depart from the designated taxi zones located at the roadway center islands, on the Arrivals/Baggage Claim Level of all terminals.
From Powell Station to Grand Hyatt