I'm on my second go around with 302 hours invested so far, first time I went the NCR and now I think I am going to back House, next time maybe Legion :shrug:
No complete playthroughs yet. My level 30 NCR supporter hit 130 hours or so and lost all motivation to continue. Currently on my second character, who hit level 24 at around 30 hours. His only motivation is himself, so its fairly simple to keep that one going.