With the timings of the shows, it is possible to cover all of SeaWorld in one day, but it's not easy. Kracken and JTA are both good rides and I'm sure at that age they will enjoy then. It does depend on how much time your vacation allows you, I would say that you really need at least one and a half days in the park to cover everything without being rushed. For example to "see" the Pacific Point Preserve ( seal and sealion enclose) if you don't stop you can walk round in probably 2 minutes, to take time, look at the exhibit, ask questions of the CMs and to watch the animals interact with each other as well as the people feeding them, you could spend an hour. Both scenarios have you "doing" that part of the park one leaves you with a better understanding of ecology and wildlife , the other leaves you out of breath and no more enriched. JMHO.
That situation can be repeated at Wild Arctic, Penguins, Manatees, Sharks etc etc. You can complete all those exhibits in 10 minutes as a total or you can take 4 hours.
In your situation, if I was pushed for time I would take one and a half days, if I had plenty of time and I was planning time shopping at Beltz etc I would probably use three half days to cover SW. That way the kids feel they have had a day in a park but you have a few hours each day to cover the things that you feel you want/need to do. IMHO if the cost of entry is paid no matter what, you don't feel you have to get up at the crack of dawm, rush to the park and stay as late as possible. It allows you 2 or 3 relaxing days, while still feeling you have "done" sonething.
