Sorry, no self-service laundry facilities on the Vista ships. I believe the plan is for these ships to do mainly 7 day itineraries so that washers/dryers are not crucial. There are 'specials' on using the ship's laundry service and the honeymooners can check on those with their cabin steward. Happy Wedding!
No there's no self-service laundry on the Westerdam.
We were on the Westerdam Rome to Barcelona cruise at the end of October last year and thoroughly enjoyed it, so hope the newly weds have a great time. I don't want to put a damper on things however, but I suggest they take some warm clothing and decent rainwear as we got a good soaking in Naples and snow in the mountains in Corsica. Having said that, it was a wonderful cruise and I would go again in a minute.