I tend to frequent gastropubs and "cheaper" places, so I can't really speak to the more expensive places and "hotspots".
Sandwiches: Pat's, Geno's or Tony Luke's for cheesesteaks, and DiNic's in Reading Terminal Market for awesome roast pork sandwiches.
Independence Mall is close to Old City, which has a few good places. If you like Middle Eastern food, I recommend
Ariana for some good Afghan food and hookah. It's BYOB and there's a state store close by IIRC.
If you like beer, consider checking out
Eulogy. They have an incredible beer selection and they make a killer burger.
Hawthorne Café is also good for beer and some great food. It's a very cozy place; they might even have the fireplace going at night now that the weather is getting colder. I used to go there a lot when I lived in that area and I've never been disappointed.
If you like German food and beer halls, you might like
Brauhaus Schmitz. It's on South Street, so you could walk around there as well before and/or after dinner.
Smokin' Betty's is one of my favorite gastropub-style places. Great food and good cocktails.