Ohio's state parks, especialy those in the SE part of the state (Hocking Hills, Lake Hope, Old Man's Cave, Conkle's Hollow, etc). There is a modern-built castle somewhere in Vinton Cy. where you can stay overnight and have a medieval dinner. Sorry I forget the name.
I love Williamsburg, my kiddos were not thrilled.
We liked Old Orchard Beach in Maine when kiddos were small (5 and 2) but we went off season, might be very crowded/noisy in summer.
We also liked Virginia Beach.
We lived in Coshocton Ohio for 1.5 years. It has a restored canal town, Roscoe Village, that is well worth seeing. You can take a canal boat ride and/or walk along the towpath. Nice campground nearby, or it was nice when I was last there some years ago!! It's not too far from the headquarters of the Longaberger basket company (marked by a huge basket).
When my brother and I were young, our parents took us all over--Yellowstone, Grand Canyon, Mt. Rushmore, Disneyland, Grand Tetons; we liked Yellowstone so much that when we took a trip to the Canadian Rockies a few years later, we "detoured" south on our way home to see it again!
We lived in Holland MI two years and loved it. They have great beaches (both state and county parks on beach), also intelligently tourist-y stuff about the Dutch (museum; Dutch Village; also a tulip-growing farm you can visit). Not far away is Grand Haven with the dancing fountains (sound and light show at night in summer). If you can go in May you can catch the Tulip Time festival in Holland--crowded but BEAUTIFUL beds of tulips! ;-) I remember heading north from there to a waterpark called Michigan Adventure, but can't remember exactly where it was.
Petoskey and Traverse City (further north in MI, still on the lake) are nice too.
One of the indoor waterparks in Sandusky, I think it was Castaway Bay (I am sure it was not Kalahari).
We spent a day or two in Sandusky area in the summer, biking in Put-in-Bay, climbing the tower, etc. They have a carousel museum there.
Lots of families like Geneva on the Lake, up here in Ashtabula County. It's one of the oldest family-type resorts on L:ake Erie. Geneva State Park is ver close by (camping available), there's a "strip" of shops and "play" stuff (mini golf, pinball, etc), numerous restaurants (wineries for parents), weekly summer concerts and gorgeous sunsets. In Ashtabula (nearby city) and points south there is a rails-to-trails bike/hiking trail that is nice.
Letchworth State Park in NY. We saw it briefly in the winter (on way to somewhere else). I'd love to go back--woods, gorge with lake (from damming a river).
Ithaca NY area. As their travel slogan says "Ithaca is Gorges". Also a nice little college town, nice park for kids, including a bike trail (if I remember it correctly).
Sometimes in the winter we just go somewhere not too far away where there is an indoor pool!
Last vacation: a couple of quick 2-day trips to 1). Kennywood (great amusement park near Pittsburgh) and Ohiopyle (didn't go rafting, but did get in the river and see the waterfalls); and 2). Bridgman Mich. to visit a family friend; we went to the beach at Lake Michigan.
So nice of you to say that any and all ideas are welcome because some may benefit others who read the post! Hugs to you, and happy traveling!
K. Z.