GustaPanino is on Piazza Santo Spirito, opposite the church – choose your type of sandwich, then your filling and sit on the church steps to eat it in the sun!  This is the bohemian, art studenty, artisanal workshop side of the city so you can do some seriously amusing people-watching here!  Students from the art school I went to (Charles Cecil Studios) often work in here, so get chatting!  The restaurants in Piazza Santo Spirito are rather lovely too, especially the one next door to GustaPanino (alleyway in between) – VERY cheap and frequented by all the local artisans and no English translations on the menu – hooray!