I didn't have time to read through all the posts so forgive me if I am repeating. Hershey is wonderful, VA has many parks. Also West Coast of FL has Bush Gardens and nice beaches.
If you want to do a beach vacation, then Long Beach Island (LBI) in New Jersey is very, very I mean very kid friendly. There is a very little theme park called Fantasy Island. There's also a water park and the typical beach stuff, mini golf etc. All the restaurants are kid friendly and many are right on the water. If you stay on the beach it will cost you, but houses off the beach are reasonable. Also you can usually go with another family. We've been doing this every summer for years.
Cape Cod is also a great place to take kids. There are many activities for them including taking a dinner train ride, being pirates on a "real" pirate ship, a cute children's museum, the beach, the bay etc.
Family fun magazine often has ideas for kid-friendly vacation.