You might have a use for this location too:
this was taken there :P
It's usually empty as it gets pretty hot when the sun is up, but you get all the lighting you want lol
This one's pretty cool too:
But both are pretty plain areas (if you're looking for more color)
Lindsay plaza has some grass and shade, but i'm not sure how the crowd will be like there.
I'd say that most of the photographing is done inside the convention center (some people "claim" a corner and set up their equipment inside). If I remember correctly, there was a photographer who did shoots by a wall inside the hallway. But you'll see a loooooot of cosplayers outside the convention center even if it's hot