Our son is 12 and Autistic/non verbal.
We always find Sea World very relaxing and generally spend 1 day there each vacation.
The water play area for children, Happy Harbor, is great.
Overall the park makes a nice contrast to WDW and Universal, and in terms of education it's probably the best.
There are allsorts of wildlife there and many children respond to these in a positve way, Joshua has always enjoyed seeing the Penguins and Puffins for example.
There is a good shopping area there too.