Our family takes in trail mix, along with the individual packages of carrots and apples. We too get the Trader Joes leather fruit.
We bring along several cases of water (we usually drive down). I also take my camelback backpack along, fill it as full as possible with ice, add some water, fill it some more with ice, add more water, continue to alternate until full. Then as the ice melts the water is still cold (we can also refill it with the free ice water from some of the restraunts). This also keeps my back cool in the hot summer.