Dear coffee shop next door to where I work:
May I suggest you examine the (lack of a) comma on your sign? I'm not going to harass you over the issue of the serial comma: it's something only writers and editors quibble about, after all. But if you want a list, then please use a comma after "public".
Because the phrase Serving the public hospital staff and visitors actually means something quite different to what you intend.
Or at least I hope it does. If you genuinely mean to tell me you're serving up hospital staff and visitors to the public, then I for one won't be partaking of any of your sandwiches in the future.
(Also: Your prices are exorbitant. That is all.)