Thanks for asking this. We are surprising our dds and going Oct 1st before our cruise. We're thinking we may go thru AAA. I will be interested in seeing all the responses.
AAA was actually more than buying online (before shipping.) They are $61 or $62 for adults and kids. I'm not sure if you can get the discount at the gate with your card or not. Several months ago Southwest Rapid Rewards was the best deal... but I don't know if that is still valid, or if something better has come along.
If you buy on SeaWorld.com, you can get the adult tickets at the kid prices. Atleast, I think they are still offering that (they were as of last week).
Other than that, the only other thing I can think of is AAA.
I think you have to buy the tickets 7 days ahead of time online to get the kid's prices for adults. That's the best deal I have found. I'm heading down the 2nd week of October.