Good questions. Now think about

it, I think perhaps it's because these brands represent certain things that one can expect. It's like MacDonald's, no matter where it is, you know there will French fries on the menu! It's interesting, though, on one hand, I love going to exotic places, and I the other hand, there is the desire to be able to rely on something that's predictable. San Francisco has quite a few nice boutique hotels. I am sure you will enjoy it if you ever have the chance coming for a visit.