GA for this set up is great cause you can attack it from any number of vantage points and not be disappointed.
I did 3 GA shows in 2015, 2 of them from the rail mid cat walk, had a decent view of main stage, good view of satellite stage and had band members pass by 2 feet from me at various points, had Larry camped out right in front of me during Sunday Bloody Sunday. Down side to that is view of screen is limited when its in use, you crane your neck and only get a partial view. Other show since my friend couldn't get wristbanded in morning, we showed up an hour after doors and got within 2 people of rail at catwalk towards mini stage.
Any spot on the floor is good as the show uses the entire floor at some point.
Saw lots of folks who would just hang back on the floor to take in the whole show, including screens, and you're still only about 15 feet max from the catwalk or stage depending on which spot on the floor you choose.