When in August are you going?
The first two weeks are peak season. The last 2 weeks are better as kids go back to school. Even if you stay onsite, it's still good to arrive early to beat the crowd. You wait at the gate before 9am, go in first, and tour the park. At 11am, the crowd hits and the walk ways fill up with lots of people, plus it is hot.
The thing with your kids, is that the 9 and possible 7 year old can make the height requirement for the coasters, and Dr. Doom. While the 4 year old won't. So you may want to let the spouse take the 4 year old to the play ground areas, while you go on the big kid rides. Take a lap around the park together, then set up a meeting place and split up for a couple hours.