So this is kind of inspired by the "Your role in the Fallout world" thread, but it's slightly different. Basically you post the nearest major faction to you and then discuss how you'd likely interact with said faction. For me the closest faction is Caesar's Legion, but depending on the canon ending of New Vegas it could also be the NCR--as I have no doubt they would stop expanding at the Utah border. As far as interacting I would most likely wind up having to serve some time in the Legion's military, and I would probably be pretty okay with my life afterwards considering Legion territory is supposed to be pretty Raider free.
Now if the NCR were to end up being the closest major faction to me I would probably be okay with that, though I'd be slightly annoyed if things suddenly went from Raider free to "You guys are on the outskirts of our territory, fend for yourselves k bye."
For the European members...speculate? Decide the East Coast is close enough to you? :I
EDIT: Tribes, raider groups, caravan companies, and the follower's count as major factions.