Just visited the Hudson Street Market in Providence's Armory District. Had the vegetarian sandwich, which was outstanding. I might go so far as to call it the best sandwich in Providence if not all of New England. I'm basing this on quality of ingredients (which is top-notch) as well as quantity (which is completely mind-blowing compared to other "sandwich" shops in town like Geoff's, whose sandwiches hardly qualify as an appetizer).
The vegetarian sandwich: they split an entire loaf of (good-quality) Italian bread down the middle and fill it to the brim with avocado, tomato, sprouts, pickles, tasty olives, hot peppers, carrots, tofu, and your choice of cheese and condiments. To the brim. And bear in mind that this is an entire loaf of bread, not slices. And this goes for: $9. A lot for a sandwich? Yes, but this one easily feeds two people, and could probably suffice for a family of four. They also have half sandwiches for ... half the price. Other sandwiches run the gamut of standards, and they're willing to make you just about anything you ask for.
Add to that great soups, homemade desserts, locally brewed sodas, friendly staff, and outdoor seating (on nice days) and you have a top-notch sandwich shop.
68 Hudson St. Providence, Rhode Island