Sure that since you heard about the pentagonal stage, you are wondering which would be the best place to see the show. Well, there isn't a better place than another, wherever you stay you will see the show perfectly.
But maybe you want to see your fave guy closer, or better. I have made a plane with the stage and where each BSB do something.
So...take a look and if you are going to go to a concert choose a place to see it.

Each BSB fly above the audience from these corners in Quit Playin Games
Each BSB climb to a fence in each corner in Don't Want You Back
They dance with the female dancers in Show Me The Meaning
They introduce a pair of dancers and a member of the band in IGBY
Where I have put a line in this color is where all of the are sitting while they sing Back To Your Heart
Where I have put a circle in this color is what in my review I call "the middle of the stage". It's a plataform, and it goes up and down. They finish almost all the songs there, and is where Kev plays the piano
In case you want to know, I was in all the concerts in front of the guitars, and I think this could be called the "Nick's side". He spents almost all the time there. I saw him perfectly.
But if you like AJ, he spents almost all the time in the opposite side, in front of Mindi.
Brian spents a lot of time in front of Bubba and Tommy,
Kev and Howie, try to be in all the sides the same time, so they don't have an "own" side.