I just wanted to mention checking your car rental through BJs or Costco Travel if you have a membership. We are doing a similar vacation, though it's 3 weeks from San Diego to San Francisco, and Alamo through Costco has a great rate for a standard, and no drop-off fee. I noticed Budget and
Avis seem to include a fee for returning at a different location, but Alamo did not. Costco had the best prices that I could find for this kind of rental.