My tux and my wife's formal dress would fill up a carry-on. There's been a few time when I washed a t-shirt or shorts that I spilled coffee on. We usually book a balcony--drying things over a chair on the balcony is pretty fast. Now that most airlines are charging $20 for the first piece of luggage and $30 for the second, I think a lot more people will be using laundry facilities or services. On our up-coming B2B we'll be taking 3 pieces of luggage at a cost $140. If we cut it to 2 pieces, we'll save $40. A full bag of laundry, washed, folded, and delivered to our cabin would cost $25. Sounds like a no-brainer.