Keeping a cooler "cool"

I've been using a combination of coleman and a knock off yeti for a couple of years ( coleman for longer). if you want ice to last throw some in before the trip and make sure everything is cold when you put it in.
yes having everything cold and pre chilling the chest works very well
 
We have long used welding blankets taped around the ice chests as well as what others have suggested- freezing what foods we could, having gallon jugs pre frozen serve double duty and for long trips have short and long term coolers designated so we minimized opening them until needed. Since we picked up a 12v combo unit, and an insulated cover for it, we have not needed as many separate coolers.