Always liked the calm of Cypress gardens, but have not been since little 'un was born, as his enjoyment would not be there
Have a look here http://cypressgardens.com/welcome.asp
We went last year and it's fine for a peaceful day out.
There aren't lots of big rides - they are all smaller kid orientated rides. A good ski show (a la SeaWorld) and so on but after an afternoon we had seen and done it all. But then it only costs $30 or so to get in.