If money's not a big concern, go with a large fridge and solar panels. It's so much easier than an ice chest AND it gives you more floor space. It's the route I plan to go one day, but for now, money is a consideration.
Currently, I'm using a higher end ice chest (Engel) and the ice will last for over 5 days and I'm never camped so remotely that I can't replenish my ice as needed. Plus, my ice chest can be used for other, non-camping, events.
Here's a link to a 7 minute video on higher end ice chest comparisons. It was this video that convinced me to go with Engel: