Make sure you visit Stinson Beach and Muir Woods to see the Sequoia Trees. Have a drink at the Cliff House at sunset. Drive the 49 mile scenic tour - takes you through the Presidio, Twin Peaks, along the coast, through GG Park, past Mission Delores and Alamo Square.
Oh, and Haight Ashbury is still a cool place. I love SF - it's my favorite place.