I don't think that there is a bad seat, granted, I've only been there one time so far. (Going to go back pretty soon.)
As others have said, they are tiered, but I don't see any problems, really. I believe that within any tier, (As someone else mentioned, you might have problems in the very back) you should have a fairly good view.
I don't think it could hurt to maybe ask to be closer to the tanks. Like I said, I've only been there the one time with my family.