In Italy, your best bet is to go into a wine bar or a stand-up coffee bar. They sell ciccetti's, wonderful snack food as well as little half-sandwiches. You can get a coffee and a half one one kind of sandwich and a half of another kind of sandwich. Have a glass of house wine and you are set for the day. If you want dessert, no doubt there is a gelateria nearby where you will have the world's most divine ice cream. Hope you don't just stick to the worldwide chains. Local food is often much better and cheaper and you will enjoy the local ambiance. Be sure to peruse the fresh markets, as well. In Venice, of course, it is the Rialto. However, every city has a fresh market. I also love the one in Paris on the left bank, is it Rue de Saint Peres? Can't remember, but I know how to get there