I completed "Basic Cruising" a week+ back and can now skipper up to a 34' sailboat (like the one shown here). I need to charter some boats a few times before I move on to the next level, "Bareboat Cruising". I'm not sure how much further I will go after that, as there is another two levels of certifications that can get you to a point where you are well prepared for full on ocean passages like San Francisco to Hawaii (that trip is about 2 weeks at sea, one way). Bareboat would let me go to various locations and rent a sailboat for days at a time without having to also hire a crew or captain (hence the "bare boat" term). This seems like a great way to vacation. I'm already looking at two September weeks in Tahiti with some friends who have the bareboat experience well in hand already.
So, if anyone wants to tour the San Francisco Bay by sailboat, I can hook you up! I think it is a great way to experience the area, day and night. Charter cost will generally run somewhere between $50 - $120 a person, depending on boat, day, and # of people.
The instructors I've worked with so far have been very good, and the rental fleet (mostly Hunters) seems very well maintained. Club Nautique is where I went, based on recommendations from others.