Feltrinelli is one of Italy's major bookstore chains. While the store isn't exactly the most unique place on the block, it's an easy place to meet up with friends for a quick bite to eat (they actually have a restaurant menu, too—not just sandwiches and pastries), a study date or just to browse through the books.
If you're waiting on a friend or need a central meeting point, RED is perfect. Pull up a chair & read or grab a coffee in piazza della Repubblica without spending "central square prices." In front they often have discounted catalogs from temporary Florence exhibitions. As for books in English, expect bestsellers, guidebooks and "airport reads."
Mon-Su: 09:30-23:00