Consider Mystic, CT. The seaport has lots of things to see & do and the Mystic Aquarium is a great place to take kids. There is a submarine museum in Groton/New London. You can also take a short day trip to Dinosaur State Park and have the young'uns make plaster casts of dinosaur tracks (take your own materials). I think we stayed at Seaport CG (this was 10 years ago now) which had a pool, etc. It may not be enough on site to suit you but there is so much to do in the area.
Lake George Escape or Lake George RV Park, NY
Odetah Campground, CT
Normandy Farms, MA
Danforth Bay OR Moose Hillock, NH
All of these are great Destination type places, been to all but one.
2007 Toyota Tacoma, Double Cab 4x4 Max Towing 6,500lbs GCWR 11,100lbs
2011 Jayco X20E, Pro Series 800lb Weight Distributing Hitch
Husky Sway Control Bar, Prodigy Electronic Brake Control
Come up and visit Ausable Chasm in the NY Adirondacks where our seasonal site is. There's lots to do for the kids. The campground now has some 50-amp sites and wifi. From here you can take the ferry to Burlington (Vt) for a day trip and visit there also http://www.ausablechasm.com/
2009 Holiday Rambler Admiral 33SFS (34' 3")
2008 Jeep Liberty - North Edition (4x4 auto)
FQCC/Camping Quebec, KOA, Good Sam, Coach-Net
Danforth Bay in Freedom, NH. Awesome facilities and close enough to the White Mountains that you can do day trips from the campground if interested. Check out their website and the Mount Washington Valley Chamber of Commerce for info on the area.
2009 Jayco Eagle 324BHDS
2011 Ford F-350 CC Lariat 6.7
How about Old Orchard Beach in Maine. Six miles of white sand (the nicest beach in Maine), amusement parks, two waterparks (Aquaboggan and Funtown Splashtown), many campgrounds to choose from (personally I love Hid'n Pines).
You're also ten miles from historic Portland with its waterfront, cobblestone streets and many boutiques.
Lake George Resort, NY
Bayley's RV Resort, Maine
Normandy Farms, MA
Acadia National Park, Maine ....many things to do and many campgrounds to pick from.
As far as on site activities, Lake George Resort has the most to offer and the entertainment at French Mountain Theater is great for all age groups.