I think Destructible bridges and / or objective points could be really cool for gameplay. Make it so that instead of defending a capture point you need to defend a part of the map, as in, you need to stop a bridge from being destroyed, or by blowing apart some wall you gain easier access to their intel.
One thing that comes to mind is the possibilities for an assault map, I dont know how many of you all played Return to Castle Wolfenstein, but my favorite map was a beach invasion map.
The defending team started in a fortress that had emplaced guns and a high wall with no entrances between them and the beach. The attacking team started out exposed on the beach and needed to make it to the wall, then either blow up a section of the wall, or blow out a door. After this they had to get into the base and capture the intelligence, then go up to the radio room to drop it off. The beach had lots of rubble and wreckage the attacking team could use for cover, and the defending team quickly realizes the emplaced guns that they have are death traps because the attackers just would launch rockets at them and you were pretty exposed. Once the attackers made it through the wall the defenders usually were forced back into the main building which had several entrances and several different ways to get down to the intel making defense difficult, but not incredibly so.
In the chat room another idea I had for a fun / gimmicky map would be that you had to completely destroy some building / object of the opposing teams in order to win, but I cant really see it going anywhere.