So i've been thinking and talking to a few people about this one, and i've been thinking Scrapyard in Fallout 3 would be a good place for a town.

pros:
Lots of scrap metal and derelict vehicles for walls and defenses
Train cars and buses could be used for housing(Just remove anything explosive from the buses) as well as a large chunk of airplane
Good location between Big Town, Canterbury Commons, Megaton and Arefu


Cons:
Close to Wheaton Armory(Raider), Germantown(Super Mutant) and Paradise Falls(Slaver)



The way i've been looking at it is a town in the Scrapyard would be more like a fort city, most guards would be using sniper rifles and/or assault rifles. If the town could find someone tech savvy, could copy Megaton and get a few robots (Gutsy bots, Sentry bots and Robobrains) for added defence. Most trade would probably be scrap metal left over from the towns construction, or scavenged materials. Could always hire mercs to take out Wheaton, which would be great for scavengers to pick through.