If you will only have one chance to ride Soarin, then hold out for row 1 if you can. I have been on rows 1 and 2 and there just is no comparison and it even is not so much the peoples feet handing in front of you. In row 1, you have the entire screen open in front of you especially above you with no spacial blocking. That's very important on Soarin as you experience the feeling of free flight. I did not feel that which section(a,b,c) really mattered, but the row(1,2,3) DEFINITELY mattered.
They que you up similiar to Space Mountain or Tower of Terror. They load you into each section with row 1 first and you stand on a dot on the floor. Once section "a" is full, they move to section "b" and row 1, 2,3; once "b" is full it's on to section "c". You then watch a short video and then the doors open(one door for each section) and rows one load first, and so on. The last people to load will be the last persons in row 3 in each of the three sections. I did see people who were destined to be in row 3 of section a, pull themselves out of line and wait for the que to section b to load and step back in line to make sure they got into row 1. A little advance planning is in order.