I would avoid those exit seats and recommend 31A and 31K (31K is my favor seat.) Remember there's a Galley there and the "snack bar" is there as well. People typically go there to stand, stretch, chat, and not to mention FAs constantly going in and out to get stuff to serve the pax. You can count on heavy traffic most of the flight.

31-row on the other hand do have the lavatory issue to be dealt with. But usually it's only busy after meals and right before landing (favor time for people to go to bathroom). All other times they are very quiet. This is why I stick with 31K and abandon the 50-ish exit rows.