I'm not a huge PVPer, but I do enjoy some PVP from time to time. However, something that constantly takes me out of it is the fact that so many battlegrounds (almost all of them actually) are in some secret parallel universe not available outside of the battleground instance. The Isle of Conquest, AV, AB, EoTS, WSG etc etc etc... they all don't exist in the game world outside of their battleground instance (I believe that the battle for Gilneas is the only exception).
I dunno, maybe I'm weird but part of the fun of an MMO to me is the game world and being a part of that world. Whatever you are doing you know that it is part of this virtual world inhabited by various other characters (players and NPC's alike). Having battlegrounds be these invisible places that you only get to by sitting in a queue kind of ruins everything for me.
I'd like to see more battlegrounds in areas that we all recognize and visit. How about Tarren Mill, a battle at the Gates of Origrimmar or Stormwind? A battleground in Ashenvale between the two cities there? A battleground in Swamp of Sorrows.... Blasted Lands near the Dark Portal? Anywhere really. I just think it would be a little more engaging.