On OZ's A380, there was plenty of room in a standard J class lav and 3times the room in the forward hump lav.
Then we got on their 777, barely enough room to rotate. Not sure how big the lavs are going to be on the new United's 777-300ER, but if its even remotely like whats on the 737, then changing into PJ's is pretty much going to be challenge.