This has become a big source of debate with my settlers group. Do you think who you sit by has an effect on the game? We now draw cards for seats. I think sitting to the left of your biggest competition so you play after them has an advantage. Whenever the pirate ship is quickly approaching playing after someone means you have the ability to react to their amount of knights. Meaning if they are in a position to lose a city you can chose not to activate a knight or if they have put themselves in a place to be the defender of catan you can foil their efforts and steal their victory point. Most likely if the ship is very close they won't have a chance to react to your move before the barbarians attack. Now on the flip side if there is a race for a placement this seating position has a disadvantage, but that happens far less frequently so I still stand by the thought that you should want your biggest competition to play before you and the worst player to be immediately after you. Now if you have 4-6 players all on a very equal skill level this may not be as big of a factor, but in a group where there is an obviously strong or weak player I think this can be huge. What do you think?
I think this is a very metagame issue. All things being equal, seating has no bearing on the game. In a way seating is auto corrected by the order of the highest dice role and the offset advantage of picking first.
If you have more experinced players playing with noobs then maybe a seating order could change things.