In my current playthrough, I came across some places I thought could be settled. I noticed the NW Seneca station (with the Ultra-Jet ghoul) and Jury Street Metro station. Both contain a few buildings one can place stores, settlers and whatever else you need and both (especially Jury) have a bit of space around them that can be used for expansions or farm/animal pens. It got me thinking that there are probably more places like that and that, one could make a quest where a group of settlers get you to help them settle at one of these places, each with their own advantages and disadvantages. Follow up quests would expand the town beyond the initial settlers, adding stores and other things to your advantage. Perhaps use of these type of assets could be to your advantage. Less work on building everything anew. Possible quests could be to convince the caravans to stop by your town or help people start up some sort of business.