Get Your Students Hired
Seems like setting up seating assignments after the fact, help in quieting a class of talkative friends. But this isn't grammar school, and right off the bat some students will feel like you are treating them as such. If you have a noisy class or certain students disrupt the class, address it immediately and take charge. I find it weak having to say, "If you can't simmer down I will have to rearrange the seating."
Take the noisy student outside in the hall and discuss the problem. Other students will know you mean business.