Also remember that those bathrooms are very popular with all kinds of folks - some with disabilities (hidden or otherwise), and some with special circumstances, and some are just Guests who want or need that moment of privacy while answering "nature's call". On more than one occasion, I have arrived at a "companion" restroom, and found a wait required - anywhere from 1 to 3 or even 4 families ahead of me.
All of that is to say to plan ahead a bit if you can; you may need to wait a bit for you turn if that type of restroom is what you plan on using. Every "regular" restroom WDW will have at least 1 handicapped stall in it (with plenty of room for a mobility device) as well.