To clarify, I definitely think there should be an admin_level=6
boundary consisting of San Francisco. I think there should also additionally be an admin_level=8
boundary, or something that denotes both levels, as I see no reason why it has to be just one or the other. But if I had to choose, I think 6
alone is better than 8
alone, in large part for the reasons @Minh mentioned.
Again, there is no sense in which “Washington” is any kind of administrative boundary. If we want to make one up, I don’t think it matters much which level we set it at. I suppose it depends if you want to lean more into “Washington is perceived as a municipality” or “counties should be space-filling”, neither of which really apply in the District due to its unique status.