Row 12 & 14 on the 737-300 are good seats, they both have 33" of legroom and at no extra cost, apart from the two window seats on 14 which are chargeable. Obviously these seats do get a bit more noise/engine vibration. As far as I'm concerned, can't beat the front row of any aircraft. The further away from the rudder the better! Obviously it's personal preference, no doubt one of the reasons advanced seat selection is so popular!