Same experience for me here in San Francisco. Easy to find good bookstores for Chinese, for Japanese, and for Korean, but almost nada for Spanish, and asking local Spanish speakers about it elicited shrugs. Ask about telenovelas, and you've got plenty of opinions, but plain old novelas, nope, so the crazy gringo part doesn't seem to matter.

I had my best luck at Barnes & Noble, believe it or not. They had a pretty good Spanish language fiction selection--bigger than any other I found on the SF Peninsula. It's not what I was looking for (I was more interested in nonfiction), but it's all I found.