I know the comfort stations that serve the 400 & 500 loop and the 900 loop have credit cards only. The 1 washer, 1 dryer, and ice machines at these comfort stations have been converted. Even the ice machine at the meadows too!
I have always put my quarters in a jar in the camper for ice and laundry while camping. I found out on our trip to the fort on February 25 that all the ice machines and washer-dryers now have been changed to debit/credit cards only.
Most premium sites you should not have any problems with a Class A rig. I do not remember which ones are pet loops. We like the 600 and 700 loop! Enjoy your trip!
I was told at check in that they can make any loop a pet loop if the Fort is full during the busying times. The CM said that if there are sites avaiable in pet loops, they will fill them first before placing you in a non pet loop. Not saying this happens all the time!