I'd like a system where people can just challenge each other basically almost anywhere that is not a duty or city. The game would set the player's stats and actions to their PvP equivalents. I don't really like the idea of having duelling areas in the city states. I like the spontaneity of people walking out of a major city and just seeing people duke it out. That kind of stuff was fun in other online RPGs. I do get the technical hurdles and exploit-doctoring it would involve, though.