tribal solar
It is no mystery to anyone that Skyrim's faction writing can sometimes leave things to be desired. Let's bring those desires to life:
Imagine that you are a designer working on the Dark Brotherhood questline. What ONE major change would you make to this questline, whether it be to the lore, gameplay, or character writing? What are its effects on the story and the rest of the game?
<@&1011584455019872266> a little outside of our normal schedule, but the new QOTW is up!
silk lintel
Same
oak bolt
Only thing I'd add is more of an emphasis on trying to uncover the traitor before the Penitus come and burn the place down. Maybe have Astrid tell us to go person by person and figure out if they have anything to do with it, which serves the duel purpose of making us pay attention to the characters before they're killed and have the eventual reveal of Astrid being the traitor be all the more impactful
Otherwise it's a good example of a guild questline done right. Simple concept that gradually escalates, and emphasis on the unique gameplay style of the faction, that being, well, assassination.
fluid remnant
Make destroying the Dark Brotherhood a proper mini questline
Or if we're going for something smaller, I would say involve the members in the contracts more. Like actually assign the jobs to individual members and have them cooperate with you, like having Babette help lure Nilsine into an alley in Windhelm for you to kill, or Nazir assisting you with sneaking into Alaine's bandit hideout
errant pond
(Destroying) Actually make it have an impact, instead of just another regular bounty quest with the teeniest bit of juice.
THE Major change would be:
tribal solar
I think I'd want more post-Emperor stuff
main yacht
Getting actual new Brotherhood recruits instead of having generic initiate(male) and initiate(female)
Its a clean slate, and as a Listener i want to make my own Dark Brotherhood
stable yoke
It is no mystery to anyone that Skyrim's faction writing can sometimes leave thi...
I'd make it so that Astrid doesnt betray you, nor Cicero try to kill anyone in the sanctuary.
I think instead they should have tried to imply Astrid would work with Maro, only for this to be one of Cicero's delusions. I think Cicero himself should be also more personable. A charmer type. Instead of being a mad jester. Astrid and her husband still distrust him thats fine, but I think his word should carry weight when spoken and not sound entirely mad. I think his madness should be subtle, less noticably pronounced.
Eventually, Maro makes his move during the Vici assassination, similar line of events but instead of learning the door phrase they simply bust the shit out of it/sideline it via a cave they've mined out nearby.
Astrid could then save the player and any survivors of the attack, dragging Maro into the fires with her.
Little bit fanfictiony at the end there but the DB is literally edgelord fanfic central Im working with what im given.
Cicero not being le funny clown man is central to this because god I fucking hate cicero
The Shivering Isles DLC has done irreperable damage to the mental illness of madness I fear
main yacht
Getting actual new Brotherhood recruits instead of having generic initiate(male)...
Like, think of it - instead of murdering Calixto, you approach him with evidence then drop an invite to Brotherhood. Now THAT would be an interesting story to see 
vague phoenix
Not killing Narfi!!!
But, really, though, the side assassinations. Most of them just... I know we are supposed to be in a guild of straight up killers, but... maybe if we got a little bit more of -Why- we are killing some of these people. And not just Narfi, there is that other guy, the one by the Lumbermill by Windhelm, that we get zero backstory about. Is he just some random hermit living out there, or what?
Meh, anyway, maybe if we could ask around to some random NPC's, and get some reasons why the Black Sacromant was done on these people, it would've been a bit better.