Great family Beach Town/Resort?

Check Kiawah Island, best beach in the Carolina's. Upscale, but not snooty. Suggest an easy day trip to Charleston, also to Beaufort. 

check out Folly Beach in S.C. its a quiet funky beach town thats a little off the beaten path. it is also very close to Charleston

Hilton Head Island, South Carolina is my favorite. Its beautiful there. Stay at The Sea Pines Resort if you want to be with other families with kids. There is not much of a night life, but there are several private white sand beaches & child friendly attractions. Close by is Savannah, Ga. & Beaufort S.C. 

Spring Lake (New Jersey) is lovely though there isn't a lot going on. Ocean Grove is quirky since it is an old Methodist camp but cute downtown and very family friendly. Bay Head has beautiful old homes. Further south is Long Beach Island though its been years since I was there. Cape May and Avalon (New Jersey) and Stone Harborare much further south and worth checking as well.

Look into Cape May

Agree with the post for Kiawah Island. Easily one of the best vacations I've have with my family (kids ranged from age 1-9 at the time). We rented a Villa. Tons of space. Great bike paths. Easy walking to the pool (which had great water features). Of course the beach was awesome too! The shopping center "fresh fields" just outside (literally) from the island was amazing! Free concerts on the green, great little shops, awesome supermarket. Just incredible.

Having grown up and lived at the shore most of my life, I strongly suggest spending your summer at any of the Monmouth County beach towns on the shore. Specifically, I would single out the more upscale towns of Sea Girt (New Jersey), Manasquan, and Spring Break, or towns like Monmouth Beach, Sea Bright and Long Branch a little more north. They are all connectable via NJ Transit and you can get to NYC in a little over an hour. The area has it all; beaches, boardwalks, great restaurants for any price range, and very friendly people. I am going to miss being there this coming summer. Good luck! 

Wildwood Beach Patrol is more family oriented and has a lot of attractions 

Seaside Park is party central

Point Pleasant (New Jersey) small boring family oriented not many attractions

Ocean City (New Jersey), NJ might be a good place for your family.  Not too crowded, nice beaches, boardwalk. Half hour drive to Atlantic City (for their outlets and/or a nice dinner).  On the way to AC, it may be fun for the kids to stop at Lucy the Elephant in Margate City. Wildwood is a 40 minute drive from OC, which is really fun (huge boardwalk!), but much more crowded than OC.

You may want to check out places like Long Beach (New York) and Point Pleasant (New Jersey), too, but I think Ocean City would be your best bet.

My suggestion would be Avalon (New Jersey) its quiet, not to touristy and has a local strip with plenty of restaurants and ice cream shops for the boys, mini golf and a bar/live music at Princeton Bar & Grill. Little on the pricer side and you do have to pay for beach tags every where in Jersey so keep that in mind but its a clean beach and not to crowded. Other suggestion would be Margate City its closer to Atlantic City and if you want shopping outlets or more than just the beach Margate will have plenty more of those options.

Hope this helps!

In addition to the other SC beaches others recommended, check out Kiawah Island. It's near Charleston with tons of nearby attractions. Very upscale and well done. Also check out Pawleys Island which is just south of Myrtle Beach. its another great choice. For a different experience, look at Daufuskie Island.  http://www.daufuskieisland.com