Laundry

Does anyone know if the princess ships have either self serve laundry or laundry service and what it costs?

Some ships do, and I think it's around $2-3.50 per load for each washer and again for the dryer. No need to bring coins...

Most of them do The Royal class on every cabin floor. They do get busy on sea days, especially longer cruises or cruises that tie in with land tours

All of the Princess ships we've been on have had a self-service laundry room.

On which ship will you be sailing?

Princess has self service laundry rooms on every ship. They also offer cleaning service.

Has Princess moved from coin-operated to either token or sea card operated machines?

I believe that all Princess ships now use tokens, purchased with your cruise card from either the vending machines in the launderettes (when not sold out or out of order) or at the purser's desk. Cost is now $3/load to wash or dry, raised from $2/load as each ship was retrofitted from quarters to tokens.

Every Princess ship has passenger laundries. All but Pacific Princess have one on nearly every deck with passenger cabins other than the topmost Lido deck which has only a couple dozen forward cabins on most of the fleet. Their location is clearly marked on Princess' deck plans both online and in their brochures. I believe the deck plans here on Cruise Critic used to omit them but a spot check of a couple Princess ships actually does show them. Studying deck plans should be one of the first courses of action for new cruisers, or old cruisers on new lines. (OP, welcome to Cruise Critic by the way...)

They use tokens, which you get from a machine in the laundry using your cruise card.