I agree with the idea of taking whatever interests you most. Personally, I am studying German rather than Spanish. However one must keep in mind that I do
nothing for just the sake of padding my application so I am something of an abberation around these parts.
Having worked clinically for over a decade, I have only encountered a few cases where there was not someone (a nurse, the janitor, one of the docs, a family member) who did not speaks sufficient Spanish to accomplish what needed to be done. Also keep in mind that just because there is not someone to translate, it does not mean care falls apart. That seems to be a common misconception among premeds. You can handle them just like you would someone who is incomprehensible after a stroke, etc. It probably will piss them off, but they are in our country and
they are the one who chose not to learn
our language.