Your experience sounds awful, and I am sorry to hear that you had to go through it. Unfortunately, it is not the first time this has been reported on FT's Marriott thread. I would not be surprised if it has happened at other hotel chains as well.

One question I have is did you get your stuff back from your rental car? You basically lost a good part of a day due to this experience and missed your original flight. Were you suppose to fly back to SFO? If that was the case, your missed flight is bad but not as bad as someone who had a transcontinental or international flight to take.

In terms of compensation, I would ask for more points if I were in your situation. If you got back your property and missed an LAX-SFO flight, I would ask for 50,000 points and the waiving of your valet fees. If you did not get your property back, I would ask for another 25,000 points to compensate for that. If you missed a longer flight than LAX-SFO, you could ask for more points or for the room certificates they give when they bump elite members. These room certificates can be used at any Marriott worldwide as long as a room is for sale. They will be reluctant to give them to you, but your situation is bad enough that you could argue for at least one if you did not get your property back and missed a longer flight.

Basically my view on compensation for you situation:

You don't pay valet for your entire stay.

A total of 50K points for missed LAX-SFO flight and rental car mixup.
A total of 75K points if you also did not get your stuff back.
75K+ points if you missed a longer flight (at least 2 time zones) or the 20K points received and additional worldwide night certificates (1 or 2 depending on circumstances).

You should keep in touch with the GM of the hotel, and let us know how it turns out.