Something that I've been thinking about would be guild based PvP tournaments on our PvP Arena. As for when it's held, I suggest one of the following: Weekly, Monthly, or Annually. As for general set up, a 5g entry fee per person, winnings will be distributed to 1st 2nd and 3rd place, and the rest goes into the guild bank for guild hall based use OR for future winnings, eg. weapon skins, armor skins, minis etc..
edit: This is more for future reference when and if we get enough people who are interested in PvP.