Where could we go in San Francisco to have a really private, personal conversation?

We need to have a long, intimate, potentially difficult conversation with someone (like an intervention), and no longer have the apartment that would have been appropriate and convenient. We are trying to think of a place where we can be for a few or several hours, without interruption, that’s comfortable and promotes openness (ie, not a public place with lots of people, or a park where people would quickly get cold or have to use a bathroom, etc.) A closed, intimate space would be preferable. Any ideas?

Secluded spot in a public park? Random hotel room? Community center empty rooms? We’re drawing a total blank.