Over-packing for a trip is a rookie mistake, and a costly one at that; pack too much and your free carry-on will suddenly become a $25 checked bag. Remember, laundromats exist in other towns, you can always run a load if you find yourself in a pinch. Or just buy a cheap pair of shorts or shirt at your destination to compensate for any under-packing mishaps. Plus, if your bag is bursting when you arrive, how are you going to bring all those sweet souvenirs back home?