I think a map like the Tug of War gamemode in World in Conflict would be nice.
For those who do not own world in conflict here is a summary
Both teams start on the opposite sides of the map, there is 3 points in the middle that are linked to each other called the "Frontline" if those are captured by one team or another, the Frontline advances to 3 more other points inside the enemy team's territory. And repeat intill all the enemy's Lines have been taken and the game is won. But if the other team recaptures the other team's point it reverts to the previous frontline
Then here is my other ideas.
Assault
You start with the other team's flag in your base, you must carry the enemy's flag into their base and into their intelligence room and score.
One Flag CTF
The game starts with a neutral flag in the middle of the map, one team must capture the flag and carry it into their base and score.
Then there is "Sabotage"
IN which in there is components(like fuel tanks,generators, computer consoles,armorys,Motor pools, and barracks) of other team's base that the your team must destroy to win
King of the Hill
In which the teams have to hold a neutral center point for a certain amount of team to win
Build the Superweapon
Both teams have to gather a specific amount of schematics to build a superweapon that they can use to destroy the other team's base