Things to do:
1) Smithville Village--a few miles north of the resort on US Rt 9. Lots of quaint shops and good restaurants. The Smithville Inn has nice atmosphere and decent food.
2) Cape May-Great restaurants..we especially enjoy the Mad Batter for Breakfast or lunch. Might be nice to take the Cape May Ferry to Lewes, Delaware. Quaint shops in Lewes and nice to walk around. They offer a shuttle to the outlets which are about 15 min from Lewes.
3) Ocean City-Nice Boardwalk with good shops.
4) Atlantic City-Fun to walk on Boardwalk. Our favorite Casino is the Borgata, though it is not on the Boardwalk. If you go to boardwalk casinos you can park at Caesars and walk north or south on the boardwalk to other casinos.
5) Wildwood-Lots of rides and 3 waterparks. More for kids, though. Wildwood has the best beaches IMHO. We live near LBI and like the beaches there, but LBI is about 40 min north of the resort.
Restaurants: My favorite casino restaurant is the Old Homestead at the Borgata. Excellent steaks. For Italian most people love Carmines at the Tropicana.
My favorite restaurant in that area is at the Renault Winery. They offer a 7 course meal and the food is great. The atmosphere is very romantic. You can take a tour of the winery before dinner and they offer free wine tasting.
The Ramshead Inn (near the GSP) gets great reviews, but I don't think the food is fantastic.
IMHO September is the nicest month of the year in NJ. Beautiful days with low humidity.
Have fun!