Here is a little advice for you from someone that has gone many times.
Get there on time, right at 9:00am. The best times to get the most out of the park is the first two hours of the day. The waters parks have been especially crowded this summer. Every chair will be taken by about 1:00-2:00pm. Get there early and put your towels on the chairs you want to keep and then go off and have fun.