One thing we brought - that my son loves even now, were quarters and pennies for the "Squishing machine". This was a great distraction, and he would keep looking for them all over the parks. helped when we got to rides they were too little for, they could look for as many penny squishers in the area while the adults road the rides. Perked them up out of bad moods because they would never know which one they could get at the machine. DS just pulled some of his squished pennies out to take to show and tell at preschool, he's gotten them out several times and has told me about where they came from and the stories he remembers that go with them.
we also brought little bubble tubes, colors and paper (small pad and only a couple crayons), snacks, and the double stroller we rented was a great idea too!