Peter Pan line gets long real quick after rope drop, always a good idea to do that first. Pooh standby definitely not as bad. But if you are very interested in seeing the interactive queue, then you almost want to spend more time in line, you could certainly do Pooh first, then PP second.
On our last trip, every time we did PP was with FP until last MK day. We went through standby queue at rope drop, and we had no idea the amount of changes they had done to the standby queue. Even though we took our time, and let people pass us, I think we missed most of the effects.