Just a few suggestions to later builds to modify quests to give the game more of a joined feeling then it has now.
-1 Courier Career Start
Objective: To give make the time skip from you being the lone wanderer to the courier seem more fluid.
How It Could Be Done: In the Union Train Station place a new NPC. Have him voiced by someone in the community. have him give out a quest where the LW will be delivering a package to the next town on the tracks, a simple job, and that if s/he does it well, he might have some more jobs in the future.
This will allow the player to really feel like they have become the courier in the time skip between the two wastelands. Side note, it might also be cool to have union station populated by refugees of some kind, a kind of last ditch place for people to go to out of desperation.
-Veronica Quest With Optional Ending
Objective: Giver Veronica's quest a bit of crossover with the Capital Wasteland.
How It Could Be Done: Give an optional suggestion for the quest I Could Make You Care. Where Veronica can accompany you and join the Brotherhood of Steel Chapter in the Capital Wasteland. It's basically the ultimate compromise between her want to help people but not betray the Brotherhood, and the East Chapter, unlike the Mojave would welcome her wanting to help the people of the wastes. Should be flagged once the LW has been made a knight of the Eastern Chapter and did not destroy the citadel.
I know that this won't mesh well with the ending slides and the dialog options would be limited since we wouldn't be able to generate more voice for the Elder Lyons/ Veronica, but I feel like it would give a real feeling of the two wastelands being connected the more options the player has to solve problems.
-Minor Tweak to the brotherhood of steel quest in the Mojave chapter, flag a few advanced weapons from the Capital wasteland to be sufficient evidence that the Brotherhood needs to change in I could Make You Care.
Examples, tesla cannon.
This is all I have for now, now back to enjoying my new wonderful mod :D