I'm so jealous :-)
Atlantic City is so much fun - we always liked eating at the New Orleans buffet (I think it's at the Tropicana). Lots of great shopping in AC, too - they "just" built outlets there maybe 5 years or so ago? DH and I spent part of our honeymoon here along with Ocean City.
Phildelphia - I LOVE PHLLY!! Make sure you eat a cheesesteak (we like Jim's Cheesesteaks on South Street). South Street is a great street filled with all sorts of people watching and interesting shops. The Franklin Institute is lots of fun and the Constitution Center is very interesting. They have "Duck Rides" in Philly,too - you take an old military vehicle (can be in water and on land) all around Philly. You get a duck whistle thing, too, which I just thought was hilarious :-)
Let me know if you'd like any other tips - I grew up in Cherry Hill, NJ (15 minutes from Philly) and DH grew up in Philly, so we know all about that area :-)