We were close to the rail towards the end of the B stage. You're right, the B stage is off to one side of the main stage - because of that we focused on getting the best view of the band within the area provided. To be honest, I could see the band on the main stage but the view was much better watching it on the backdrop, and the graphics were "amazing". Only speaking for myself here, but given the chance to be as close as we were was worth it. The odds of getting that close in regular GA are probably pretty slim and the main stage is really high so being up front doesn't give you a great view.
I hope you have a great time! It is an amazing show and you will have a great opportunity to be on the rail of B stage (try for the back, it's the best view of the band).