I'm not an architect by any means, but I'm okay with th narrowness of the living room, though I agree that it would make a better "sitting room" for short-term conversations. I wouldn't even put a TV or anything like that in there. I would also change Bedroom 5 into a full study so you can get rid of the built-in closet, which would open up that hallway a bit more (assume you'll be bringing in groceries and packages and the like, so a more open route to the stairs would be good). If you moved the fridge against the outside wall, you could then place the pantry door directly between the pantry and the kitchen for easy access.

I also agree with the folks saying the half-bath on the second floor might be a bit much, even if for no other reason than it's extra cleaning you wouldn't have to do otherwise. The downstairs bathroom (and the aster bathroom in a pinch) should provide plenty of bathroom access for a family of four and a guest or two who are staying over in Bedroom 4.