From what I saw whenever I was there, Oceana was a popular attraction. I think that the only reason that they got rid of the dolphins is the fact that they got a disease and some of them died off. They decided not to replace them for some reason, but I don't know what that reason is. (I think it may have had something to do with the penguins and dolphins dying. I'm sure some animal rights activists complained about it.)
However, you are right. There is plenty for kids to do at Cedar Point. There are lots of kiddie rides. Camp Snoopy (probably the best themed area of the park). The Petting Farm. And lots of flat rides that little ones can enjoy with their parents. Plus there are some enjoyable shows, the train, the paddle wheel excursions, etc... My five year old nephew loves Cedar Point. In fact, I think that he enjoys it more than he enjoyed Walt Disney World, where loud noises on many of the dark rides scared him.
Ohio has three great family destinations with Cedar Point, Paramount Kings Island, and Six Flags Worlds of Adventure. They have all been successful for years (even if under different names in some cases) and they will all continue to be successful as long as they are run well.
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...and enjoy the rest of your day at Cedar Point, The Am-aaaa-zement park!