Lots of interesting ideas here! Personally I was thinking of maps like this,
Basically each side has two lines of trenches and there are also some features of no man's land scattered about. Conquest will be played as normal, hold more flags and kill to deplete the enemy's points. Capturing one of the no man land's flags will pretty much give your team a foot hold to spawn on and launch more attacks on other no man's land flags or the enemy trench itself. In the same way, capturing a section of an enemy trench will give your team an opportunity to keep pushing and eventually conquer the enemy. Both teams have to respond immediately to lost trench sections to prevent the enemy from launching more attacks against other trench sections. The idea is that when you take flags, it gives your team more opportunities to move forward.
This can be tons of fun in squad based events. They'll need to coordinate which points to attack and defend and figure out which flags are needed most.