@feklee, perhaps yours from Germany didn't; but almost all Visa and MasterCard cards I've seen in the US of A, include car-rental auto-insurance free of charge (they only cover rentals, and only those you pay with the card, and when you decline rental company's insurance). Here's the FAQ on the policy: usa.visa.com/personal/cards/benefits/…, and here you can see that all VISA credit cards in the US of A market have this benefit: usa.visa.com/personal/cards/benefits/index.html.

When going to the Bay Area, one should probably worry more about the cost of the hotel, than the airfare. For example, for weekdays, it's not uncommon see hotel prices way into the triple-digit numbers (even in San Jose), although weekends are generally much more relaxed (at least in San Jose, not so in San Francisco).

btw, this is a partial answer, which doesn't actually answer the question yet, but just provides a starting point for now. :)

yeap, exactly; most credit card policies I've seen say that they only cover what's not covered by other policies; and, you can only get their coverage if you decline the coverage that's provided by the rental company (which is, perhaps, a funny way of saying that they only cover what's not otherwise covered :). Somehow, so many people don't know about this!

@feklee, the amount not covered by an auto insurance policy is exactly what most credit cards cover; to have such coverage from most VISA/MasterCard CCs, you have to decline coverage from the rental company.