I generally do a good guy playthrough siding with the BoS while donating tech to the Outcasts for the goodies. I exterminate the Raiders in the Pitt with a twist, I leave the mom alive by knocking her out and using a mod that lets me tie people up. Then I sort of drag her along while clearing out the area of raiders and trogs. Figured that'd be the best way to get a cure while also smashing the shit out of the slaver scum. I save the slaves and purge Paradise falls, but not before buying Clover because why the fuck not. The Lincoln Memorial is also secured. Megaton is saved, Tenpenny Tower remains Ghoul free because fuck you Roy Philips bigotry is not a crime worthy of death and besides Herbert Dashwood was no bigot you lying zombie faggot! Vault 101 is allowed to remain closed for awhile with Amata as overseer.
The entire reason the LW goes out west is on assignment from Elder Lyons to make contact with the California Brotherhood and update them on the Enclave and 87 Mutie situations. Star Paladin Cross accompanies him, as do his trusted servant/soldier Charon, his bodyguard/slave Clover, his good pal Fawkes, and his beloved doggo.
Learning of the NCR-Brotherhood war from the western Elders and believing it to be folly on the Brotherhood's part the LW and Cross were released from service from the Western Brotherhood on their own request.
So the LW does what any bored wasteland hero and his gang does, he starts wandering around and working, eventually making his way to the Mojave where he gets a job as a courier until being blammed in the head by Benny.
When I discovered the town of Nipton and I was enraged as hell, my first impression of the Legion being just another band of murderous thugs to put down. I slaughtered Incultes and his men, mercifully put the crucified out of their misery, then followed the rest of the bastards to their camp. Discovering the enslaved powder gangers, I rescued them (even though I already pissed of their gang when I led the people of Goodsprings against them. Still, noone deserves this shit.) and put down the Legionaries there having developed a decided distaste for the bastards.
I eventually came to the Fort and assassinated Caesar and most of his bodyguard before shooting my way out and running like a motherfucker.
At the battle of the Dam I would kill Lanius in single combat, sword to sword. Once I'd cast him down I would declare myself the true son of Mars and issue my ultimatum to the legion:
Sumbit or perish, submit and thrive. All your base are belong to me!
Working primarily for the NCR throughout my travels, often completely unasked, I eventually betrays them at Hoover Dam using the Securitron army, my own private army of reprogrammed robots amassed in my travels, and a rather large collection of loyal followers.
But the betrayal isn't quite what you'd think. The Lone Wandering Courier of legend agrees to allow New Vegas to be annexed into the NCR on several conditions:
1: I am to be installed as lifetime governor of New Vegas and cannot be removed under anything but emergency circumstances such as proof of treason.
2: The area known as Zion is to be granted its full sovereignty and exempted from any NCR expansion.
3: The city of New Vegas itself is to be the sole property of both the Courier and Robert House.
4: The Boomers are to be given total sovereignty over Nellis.
5: I am named the official ambassador to the Brotherhood of Steel.
6: The Great Khans are to be left alone and allowed to live as they see fit within the confines of their canyon.
7: Amnesty is to be offered to all Enclave remnants. They may be required to register with the NCR and turn over any Enclave equipment they have remaining.
8: The settlement of Jacobstown remains it's own community under Marcus. Super mutants are to be allowed to peaceably settle there.
9: The current deal of 95% power to the NCR and 5% to the Strip remains, but Helios One will now exclusively provide power to New Vegas' needs.
10: New Vegas is allowed to form it's own army which is technically part of the NCR but also technically not. The Courier will act as commander in chief of this force.
House I would keep alive, despite taking the Yes Man route. I would use my big brain science knowledge to find a way to keep the power to his life support pod active and keep it closed, but I would terminate his connection to all outside data points which would allow me to install Yes Man into the Lucky 38 and proceed with my plans.
Once all was said and done I would sit down for a little chat with House, telling him that much of his plan was agreeable to me, but other parts were not and his refusal to bend necessitated a hostile takeover. He's a businessman, surely he understands
I would renegotiate the terms of our relationship, demanding full partnership in the affairs of the Strip and a cut of the profits. House can have his high tech sector, but I have my own plans that also need financing and a base of operations. House would still get the lions share of the money flowing into Vegas, but I'm taking 10% for my own uses.
The Brotherhood and NCR would have their truce under Elder McNamara, but I would use my knowledge of McNamara violating the chain of command to blackmail him into doing as I say. Namely that when Hardin eventually suffers an unfortunate accident that will inevitably be labeled as an equipment malfunction my good friend Star Paladin Cross will be assigned to take his place given her ranking in Lyons Pride. The hardliners will be reassigned to duties outide the bunker, scavenging tech from far away locations that keep them out of our hair for good stretches of time, with some of the most hard headed perhaps not returning from their dangerous assignments.
The more progressive elements would be allowed to flourish under my own influence, as well as that of Veronica who I would have encouraged to stay, and Cross. The Mojave Brotherhood would return to Maxsonian ideals and become more like the Lyons Pride.
Eventually I would set my sights on reforming the rest of the western Brotherhood, but that's a campaign for another time.
Freeside would be incorporated into New Vegas, with new casinos and businesses encouraged to open in the abundantly available abandoned buildings. Cerulian Robotics would become my personal robot manufactury to bolster my forces.
The Kings would be given the role of Freeside Police, with new weapons and combat armor supplied from the Gun Runners with my own money.
The Followers would be encouraged to found a research institute under House, as well as being proded to open a proper hospital in Freeside with regional clinics at every major settlement.
The Fiends of Vault 3 would be completely and ruthlessly exterminated without mercy. The Vault would be retaken, refurbished, and reserved as an emergency shelter as intended.
All raiders in the Mojave are going to be hunted down like dogs and given absolutely no fucking quarter.
I would encourage the NCR to offer some quarter to surrendering Powder Gangers, though those who do not take this offer are to be executed.
Father Elijah I would trap in the basement of the Sierra Madre, leaving him the chips he needs to run that fucking replicator. I would eventually come back (because my ass you can't find your way back. You have a goddamn map making computer on your arm!), dig him out, and enslave the old fuck. I'm gonna stick him in a goddamn lab and make him do science or I use a slave collar to blow his fucking head off.
Dean Domino I just shoot in the face. Fuck that prick.
Christine I would eventually try to convince to come back with me because someone is waiting for her. They can finally be together. The Sierra Madre will be fine, my own forces will secure it and it will be plundered for the tech and eventually demolished with bombs.
Speaking of bombs.
The Boomers I would leave be, mostly. They owe me, tho. I want them to be the founding members of the New Vegas Air Force if they'll agree to it. I would give them plenty of savages to bomb.
Oh, and I would indeed nuke Dry Wells during Lonesome road because FUUUUCK YOOOOU!
The Think tank I would convince to stay where they are, but I have use for their kooky mad science! So many puzzles to solve in this new world, so many challenges, so many ways to ethically apply science! And maybe they could become part of my institute! Remote access to Big MT could be established to allow them to coordinate and collaborate with other scientists to benefit mankind.
The Remnants would be allowed to retire in honor, heroes of the Mojave. Those who choose to do so can join my personal army, an army dedicated to protecting people from the dangers of the waste and making America great again! The New Vegas Armed Forces. (technically a subsidiary of but not necessarily answerable to the NCR Army)
Eventually I would incorporate former Legion territory into my own through force if need be, though as the guy who killed both Caesar and Lanius I probably just get to claim right of succession through might and fuck anyone who says otherwise. And hopefully Lucius appreciates that I spared his ass when I killed Caesar and backs my play. I could use men like him. Honorable men.
Either way, the New Vegas Army would take the area and absorb the rehabilitated Legion remnants, then simply hold that territory as a state of the NCR while still enacting the same ruthless justice the Legion did on any raiders who are caught there, though the laws would be changed to be less restrictive and allow a lot more freedoms.
Pretty good way to start my political career, doncha think?