we've done the chain before, too. it works really well unless the kids are so tiny they don't understand why you can't take them all off NOW, lol!
this year, we're just using a giant calendar. we use it for homeschooling, and the kids stick the dates on each day (they stick with velcro). since they understand how a calendar works, they can see how many days we have until we leave (just 5 more, YAY!!!).