Hi,
You should definately go to SeaWorld if only for a day. The one in Australia isn't actually associated with the USA one.
SeaWorld has an Awesome Killer Whale show and is a Must see. These animals are not in captiity in Australia and is worth the price of adission just to see. The SeaLion show is also good and is funny.
Are you thinking of SeaWorld Orlando, San Diego or San Antonio cuz I think each one has different rides.
Orlando had Kaken which is a roller coaster with lots of twists and turns, Journey To Atlantis is a splash drop ride similar to Splash Mountain, Wild Arctic which is a Virtual Simulator and when you get off you see polar bears and Beluga Whales. They also have kid rides but the above are the rides I went on.
HTH