I'm alliance... so I will take a tower.
Which usually means it is vacant, my toons follow me up, and then guard the tower against recap attempts.

I will position each of the DK's within the tower, two on a side (so they can "see" diagonally outwards as enemies approach from one direction, while those enemies cannot "see" the other two DK's).
I enable my Death Coil mapped key, which is a toggle; this gives the team more ranged power.
I disable my Melee IWT, another mapped key toggle; now my team will not run anywhere no matter how I spam my DPS key.
I have my finger over the Trinket, to break a fear attempt immediately.
I'm also ready to Lichborne, if I see a Priest/Warrior/Warlock approach.
With Enemy Cast Bars on, and coloring enemies by class, I can see what class is approaching (through the wall) before they get to me.
My Paladin usually stands outside, on the ledge, so I can heal those below as they run past.

When a group is holding the tower...
I disable the IWT, and enable the Death Coil.
I use follow, and activate the defensive cooldowns - just before coming to the entrance.
The toons are immune to almost everything for a short while.
And will Howling Blast / Death Coil, a lot... from the entrance, and will get everyone inside (with the AoE attacks).




When defending a Bunker...

I move inside the bunker, but stop at the foot of the steps.
And turn back towards the entrance.
I enable my Death Coil, to help drop whoever enters before they run past me.
Usually it will be 2-3 running in, and 1-2 will die before they pass me.

Any that pass me, I will Death Grip back down to the entrance.
And fight in the room down there.

If they get past me, I treat the bunker as "taken".




Recapping a bunker that has been "taken".

As I enter, I have each of the DK's call their Ghoul pet.
Which has NPC's that don't run off edges etc... on the opponents asses, making it harder on them.

I generally run in, and click Anti-Magic Shell, as I'm going up the stairs.
If the Pally is CC'd/Feared/etc, and the Human Racial is on cooldown, I'll switch to a DK.
Otherwise they follow the Pally up.

I disable my IWT mapped key, and ensure my DC is enabled.
I run to the top of the stairs, or sometimes stop midway up and kill anyone who is visible up top.

Once no one is visible, I run to the top of the stairs.
And then run back down a tiny distance, so my toons are now facing the flag.
I do my spread out key, very briefly to break follow here.
From there, I will spam my DPS key, which is Howling Blast (AoE/Ranged), Death Coil (Ranged)...
And once I'm out of Runes/Runic Power, will Death Grip someone across to the DK's.
The DK's quickly kill anyone.

Once everyone is dead, I re-initiate follow.
Run them all to the flag.
Switch to one of them, who moves to break follow and then clicks the flag.
The others will jump down to the "taking" position, and I'll Death Grip anything that interrupts the re-capping (which is not often needed).




This seems to work 95% of the time.
But three players who know their classes (Priest, Warlock, Warrior) have, in greatly inferior gear to me, locked me out of recapping a bunker for over a minute.
I know their gear sucked, because I got them very quickly and very easily... once the bunker burnt and they came out to level ground.