I was in sec 20 for May 26.
personally, I think for the money - you will be happier with the prices for 15 and 20 over the prices for the other sections you mention. 15 and 20 are the best seats in the arena for the money.
Last row is 21, first row is 11 in both sections.
I'm in SEC 15 on Monday and can't wait. My experience in SEC 20 was fantastic in the spring, and I can't wait to be on Edge's side this time.
As for how much time Bono spends on eac side. My experience from the Boston shows and seeing video is that he has spent a bit more time on Adam's side this tour, but that may be more of what I have noticed. I just think he has gone down that side ramp more on Vertigo. I also think it was the opposite on Elevation.
As for Row choice, I don't think it's a big deal. You are already elevated 10 rows up. The first row in 20 or 15 is row 11. They only use the first 10 rows for basketball. 11 - 21 are the rows you can get. As for seat numbers, seat 1 always starts on the left side of the section as you are looking at it from the middle of the arena. Thus, if you are seat one in 20, you are to the far right of that section on line with Larry's kit. However, if you are seat 1 in SEC 15 - you are at the tip of the main stage.
Hope that helps. I'd go with whatever seats are closer to the front of the main stage. I wouldn't be so concerned with the row number.
It's a great view - good luck.
daveydave