There are many kind of PvP events:
1v1, 2v2, 3v3, 5v5 events: These events should be hosted in one of World's arenas (I prefer Blade's Edge Arena). Players will make tickets with their names and GMs will summon them. When event will start, GMs will port players (teams) down into the arena to fight each other (One by One). Only three winners (Three players / teams) will be rewarded. (PS: PvP is allowed only to teams fighting down and only when GMs will start their fight!!!).
10v10 = Alliance VS Horde (AvH): Players will make two teams and will be ported to a good place for this event (I prefer Azshara Crater). It's like Battleground but when you die, you must NOT release your corpse and ressurect yourself. Team that survives will win. Both teams will get rewarded (3:1) = Team that won will be better rewarded. (PS: PvP is allowed only when GM(s) will start the event).
These events should be hosted once per 2 days.