I remember many moons ago a siege map that was a giant tower. Defenders spawned at either the top floor of the tower, the middle of the tower and sometimes outside the tower. Attackers would try to make their way to the top floor to cap the flag. The tower was about 10 floors so it was quite a grind to get to the top.
It was a bit bugged as the stairs in the tower would make you schiz out. The map was crap in the state it was, but it was an AMAZING idea non the less, it just needed some updating, balancing and tweaking.
We need more creative maps like that where the enemy cant ninja cap the flag and where the defenders and attackers feel really proud and accomplished once they've won.