Pier 39 is the busiest, most unashamedly commercial stretch of Fisherman's Wharf — a two-level boardwalk of shops, restaurants, carousel, and street performers jutting out into the bay. It is touristy in the extreme, but it has one genuinely wonderful free attraction: the colony of California sea lions that hauled out on the floating docks at K-Dock after the 1989 earthquake and never left, now numbering in the hundreds and barking, jostling, and sunbathing to the delight of onlookers.
Beyond the sea lions, the views from the end of the pier across to Alcatraz, Angel Island, and the Golden Gate are excellent, and the bay-facing benches are a fine place to eat something from the seafood stalls. Treat the shops as scenery rather than a destination, watch the sea lions, take in the view, and move on to the quieter parts of the waterfront.