We've done the paper chain countdown many times. It's an easy way to build the excitement for an upcoming trip. Like they aren't excited enough.
Have the kids make a display with a sign and paper chains to count down the days. Make one link for each day that's left before the trip, plus the day of the trip. Each kid gets to tear off a link at bedtime for each day that passes. The last night before the trip there will be one link left to tear off, and the link that is for the day of the trip can be ceremonially taken down as you go out the door.