If you're a fan of hoagies, I strongly recommend the old-school italian from Shanks on Columbus Blvd. If sausage is more your jam, get a sausage sandwich from Rocco's at Home Depot also on Columbus. Philly has some amazingly delicious shack food.
When sandwiches in philly were my diet I'd hit up Paesano's every once and a while for a different take on the standards, looks like they kept the place on 9th. Cheesesteaks I was a Cosmi's guy. Hoagies, a deli in Wash Sq West, but only when a particular guy was behind the counter.