In general, most San Francisco streets are in pretty good condition, when compared to other major cities. Thus, there's little use for wider tires. Narrow tires with a CF fork should work just fine for you.

OTOH, I've found that comfort is usually associated with wider tires, at the expense of speed and efficiency. Of course, you could have the best of both worlds with a Touring bike that can be outfitted with wider tires just like the CX bike.

Usually chromoly steel frames and forks come with Tourers. A tourer with size 32mm or greater tire should be just perfect!