Determine meeting times and places in advance. Unless you have a clear meeting place, you can spend half the day looking for or waiting for each other. This can create some BIG family fights. Before you go to the park, talk to your kids about what to do in case they get lost. Most parks DO NOT page for missing children.
Long lines are the most common frustration at large parks.
As you enter the park go to the left. A study has shown that most people unthinkingly go to the right. Also go to the back of the park and work your way forward. Most people stop in the front of the park at the first major attraction that they see. Many shows and entertainments are held in air-conditioned theatres.