What type of paddling are you interested in and what are you interested in seeing? There are many great spots along the coast to paddle depending upon the ocean and weather conditions. Morro Bay is a great spot as well as Monterey Bay and the Elkhorn Slough. These spots have kayak outfitters who rent kayaks as well as offer guided tours.
Paddling in the San Francisco area is tricky because of the tides and currents. For paddling that area, I would recommend a guided trip. Sea Trek comes to mind as a reputable outfitter.