Should add that there is a Vapianos right outside the Marriott, and that's an inexpensive chain that I've been to in Frankfurt, Nuremberg and Munich. You place your order at the counter and they give you a pager that activates when your freshly-cooked meal is ready. Think around 10 euros for a main course (pasta/pizza). This one always seems pretty busy in the evening.
http://de.vapiano.com/de/magazin/