DH's whole family and we are making into an annual event. But we camp at Ft Wilderness for 4ish days and have yet to buy a park pass. At the campsite, there are movie nights, a pool and splash park, playgrounds, and you can take a ferry anywhere and hop on the monorail.
There's lots of us to do without actually going to a theme park. The oldest kids are only 3 now, but might go to the Magic Kingdom next year or the year after (kids will be 5, 5, 3, and 2).
ETA: All our family lives in FL, north of Tampa. We're the only ones out of state, and we're just in GA, easy drive.