There's no difference between the lines. Some THINK the no line is noisier cause they need a subconscious justification to dump more money on a line. Outside of the steering/suspension on the msport and sport, all the lines do is add some external trim and some interior color options.
As for noise, there's been some complaints about wind noise due to the front windshield not being glued properly, or some rattling/buzzing due to HUD, but again, test drive a few and feel for yourself. The 3 series isn't designed to be a quiet highway cruiser.
If you want the quietest car possible, go get an activehybrid, or even a 5 series (550 is actually quieter than 528/535, since bigger engine means it needs less revs/power to reach same speeds)