I love Busch Gardens! Water Country USA was a lot of fun when I was younger, but I haven't been there in years.
I live in Delaware, and even though my kids and I are Disney fans, we can't always afford to go every year. Instead, we do the following:
Wildwood: Morey's Pier is awesome!
Cape May Zoo: Over 250 acres, 200 animals, and is completely FREE!
The Delsea Drive-In: $9 per person for two films, you get to sit in your car, tune in your radio, and eat delicious (& varied!) food from the snack bar... it's a lot of fun!
New Jersey State Museum: In Trenton, there's a nice planetarium, which is much cheaper than the one at Franklin Institute.
Linvilla Orchards: Just off of I-95, in Media, PA, there's fruit and veggies to pick, a fun playground, animals, hayrides to their fields, markets, and Pumpkinland (in the fall).
The Poconos: It's more popular in the winter months, but can be fun in the summer and fall. Check-in out Bushkill Falls Park, and the annual hot air balloon festival.
Knoebels: One of the last great amusement parks! It's free to park, free to get in, and rides accept tickets ranging from $.50 -$3, which you can purchase in a book. This park has won awards for its food, and has a nice swimming pool, and one of the best wooden rollercoasters in America: the Phoenix. You can camp here.
Herr's Potato Chip Factory: This free tour shows visitors how they make their snacks, and gives free samples! The gift shop is small, but their "oops" bags are worth buying.
Hersheypark: Sure, it's a park with cool rides and a water park area, but it's got a zoo, a free tour, and it's all about chocolate! Yum. There's camping here, too.
Busch Gardens Williamsburg: It's my favorite park, outside of Disney. They have themed areas, like Scotland, Ireland, Italy, and Germany, with amazing coasters, delicious food, and a beautiful park. It's especially awesome during the holiday season, when it's transformed into Christmastown. For 21 years, this park won the "Most Beautiful" award. It's worth a look, as long as you go with an open mind; they aren't looking to be Disney, and you shouldn't expect it... but do expect to have a good time!
Colonial Williamsburg: I admit, I don't usually go into the buildings when I visit, but they are impressive, and the people who dress in the period clothing and are part of the exhibit are pretty amazing. There's so much one can learn from this place, about the history of our country, and it can be fun!
Longwood Gardens: We love to visit at Christmas, but Spring is also a lovely time to go. So many beautiful flowers!
Delaware Children's Museum: It's best for kids under 10.
Brandywine Zoo: 12 acres of zoo, with some cool animals, like a tiger, capybara, river otters, owls, and during the warmer months... tamarin monkeys!
We also have gone to Philly, to see the Liberty Bell, National Constitution Center, and the Flower Show. We've been to Dover and Rehoboth Beach, DE... Fort Delaware, Wilmington Blue Rocks games, Dutch Wonderland, and Milburn Orchard.
I used to work at Great Adventure, but don't go there anymore; it's not as fun as it used to be. There's Clementon Park, which has a waterpark, but as I haven't visited since I was a kid, I don't know what it's like, now. We might try it this summer!
The point I'm trying to make is that there are so many fun things to do besides (or in accompaniment to) Disney. I know, it's almost a crime to say that on here, but when you try new things, your kids are more likely to grow up with a broader mind and have knowledge of fun facts and places that their peers might never experience! I hope you have fun, no matter what you choose to do!