For what it is worth...
My wife has family in the Orlando area (St.Cloud to be exact), and she likes to go down there and visit at least every other year. We were there in March of this year, so that means March 2003 will probably be our next visit.
In our last visit, we went to IOA, Sea Wrold, and BGT. Of those three parks... I would rather spend the money and go back to Sea World and BGT (even if they do not get new coasters) than go back to IOA. In my opinion, Hulk is good and Dueling Dragons is mediocre. (as for Spiderman... two times is fun, but not much of a re-ride value). At Sea World, even though they have only two thrill ride attractions, Kraken and JTA are worth the admission price alone! BGT is the same way... we spent one day there just doing the rides (coasters, water, etc) and didn't even get around to seeing many of the animal exhibits (We also missed the shows and such at Sea World as well).
Our game plan for next trip... get to BGT and of course do the coasters (at least Gwasi, Montu, and Kumba) and concentrate on the wild life exhibits. Same for Sea World... go back there and take in alot of the wildlife exhibits that we missed last time around. The other side trip will (hopefully) be to Dania Beach for the Hurricane.
As far as IOA... ONLY if they add something new (and something big) will it be enough of an enticement to get us to spend the $ and go back there again.
So, to answer the question... of the three parks that we have been too...
Sea World (yes, even with only two thrill rides) and BGT were worth the $ (enough to make us revist on our next trip). IOA, while worth the cost once, is not worth it for a revisit unles something major is added.
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"I wasn't always this cynical, but then I started kindergarden..."