Actually, every third-party site (that has worked for me in other parts of Calfornia and/or on other dates) that I've tried shows higher rather than lower rates for these (if they show either at all). So I suggest you might want to book a refundable rate at one of these soon, if you haven't already, in case no LNF shows up and you absolutely need one of these properties. (There are other Marriott properties nearby that are a lot lower on Marriott.com -- Renaissance Stanford Court, CY Downtown, Marriott Fisherman's Wharf -- but presumably they're not right for your needs.)

If someone does find you an LNF, you can always cancel your refundable rate and book again (given that you have to submit an LNF within 24 hours of booking) if it's at the same hotel, and if it's at the other hotel book and confirm the LNF first before cancelling the refundable at the other hotel.