I would love to see a map in Stormwind City. I picture it as something like the legendary tournament venues of the Medieval Knights. There would be banners all around it and an audience of noisy NPCs in the stands. In order to spice things up, it would be awesome to include environmental hazards like boiling oil or escapable, but painful pit traps. Also, if I were designing an Arena, players would be forced into combat more quickly, since the preparation areas would close one minute after the battle began.
It would never happen, but a girl can dream. If you could design a battleground for Arena combat, what would it look like? What new features would you add?