I second the collapsible cooler. Use it during the week, then, on the last night, empty it out, dry it out and fill it with souvenirs, protect 'em with dirty laundry, towels, etc. and check it as luggage. We usually lock it with an electrical tie, then put a strap around it. (You can buy the strap at Wal-mart, near where they sell the luggage) Hope this helps!!!