One of the things I hate when camping is having to find ice every couple of days. A friend of mine turned me on to a cooler insulation insert called the KoolerCap. She told me that my ice would last...
I always freeze a gallon jug of water and put it in our cooler. Depending on where we are, it usually stays frozen for 4-5 days and keeps everything else cold in the cooler, too. Sometimes I freeze 1/2 gallon (flat) plastic jugs of water instead of the gallon.