Well then how about this?
An event weekend called Mirror World or something like that, Every map is the same except the roles are, Reversed! Here's a greater detail example:
Alliance Battles
These are fairly balanced to begin with for the most part, so the only thing that's reversed is which spawn point belongs to which faction
Jade Quarry
This is similar to the alliance battles, all that will change is which side each faction spawns on. Sort of for the sake of the name of the event xD
Fort Aspenwood
Okay now here's the big one, a complete and utter swap!
Kurzicks will own the green mine and two command points at the start of the battle, and on top of it they'll be the ones attacking. Architect Gunther will replace the monk on the green mine, Gatekeepers Poletski and Radick will replace the Orange and Purple Commanders, and will be accompannied by an archer and a ritualist
When a Luxon captures the purple or green mine, the keepers will still be 2 archers and when a kurzick captures a normal mine the keepers will still be 2 ritualists.
However, when a luxon captures the green mine, they will be replaced by 2 luxon archers and 1 monk. When a luxon captures the Purple or Orange command point they will be replaced by an archer and a monk (following the same skill sets they have in the normal FA)
To make things interesting, a replacement for the turtles and warriors on offense is 2 Kurzick Siege Juggernaughts and 2 domination/inspiration mesmers
The outter gates defenses for the luxons will be 2 archers and 1 elementalist
The inner gates defenses for the luxons will be 1 archer, 3 necromancers on the orange side and 2 mesmers, 1 archer, and 2 elementalists on the orange side
The Inner Gates Sanctum (between the green gate and inner gates) will be protected by 2 archers on either side of the portal (in the juggernaught route) 1 elementalist and 1 necromancer.
The Green Gate will be protected by 2 turtle turrets and 1 monk
To win the game the kurzicks will need to kill the Fort Commander, ranger. Guarded by one protection monk and one healing monk.
To go even crazier into detail I even thought up the skill sets for specific people

The Fort Commander will have:
Charm Animal (Crab Pet), Melandru's Shot, Apply Poison, Distracting Shot, Lightning Reflexes, Pin Down, Troll Ungent, Throw Dirt
The Green Gate Monk will have:
Karei's Healing Circle, Ethereal Light, Healing Breeze, Healing Touch
Turtle Turrets will have the same health as the regular juggernaught and:
Turtle Shell, Turret Strike (Adjacent AoE and 1/4 the damage of a regular siege turtle attack)
The mesmers that go with the Juggernaught will have:
Complicate, Power Spike, Energy Burn, Energy Surge, Ether Feast, Mind Wrack
Siege Juggernaughts will have the same health and speed as siege turtles and will have:
Aura of the Juggernaught, Juggernaught Throw, Hurl Rocks (same damage as siege turtles but single target)