Yes, there are self service laundry on every guest deck, shouldn't be hard to find. I think the cost was $1.00 for washer and dryer, they did have coin operated machines for detergent and a dollar bill changer that seemed to always be empty. If you think of it, take some quarters from home and you'll be fine. Another nice feature about Princess, sure saves on the packing if you know you can do a load of wash during the week.
The laundry seemed to be busiest on the second sea day from what I've observed. It would probably be pretty vacant on port days. If you stay on the ship, it would be a good time to do some. I only had to wait once for a machine. There are laundromats on just about each deck, so if it's closer to go up/down a deck that's what I do. I brought a roll of quarters, sometimes the change machine is down. Many people wouldn't even consider doing a laundry while on vacation, but I don't mind. I'd rather do that than haul an extra suitcase!
Me too, plus when you return home, you don't have mounds of wash to do, just unpack and do a little wash, sure makes coming home from a cruise much nicer. Now, if we only had someone to cook/clean for us :-)
The laundy rooms are much less crowded on port days. If i decide to throw in a wash i usually do it when we return from port, just throw it in and leave it until its done. Another good time to do laundry is during the dinner hours. If you have late seating do a wash during the early seatingand visa -versa