Carrier Warfare (think of Air Superiority from 1943)
There are two Aircraft Carriers, and the other teams goal is to destroy the other's.
For example: One could bomb the runway of the air craft carrier, an engineer could blow up sensetive areas, recon could bombard the ship with morterss and so on.
The idea would be the whatever team to destroy the other's carrier would win.
In the center would be a small island, that is basically an air strip and some boats, so whatever team has that can quickly get to the enemy's carrier faster.