Even if the neck was constructed with a semi-monocoque design where the skin bears the stress of the load (eliminating the need for space-robbing, truss beams), there's still not much wiggle room in there.
That narrow space doesn't seem to offer anything functional for the crew, either work-related or recreational. It would be more appropriate to have an "officer's club" or crewman's lounge located in the widest portion of the ship - the main deck (deck 7, if you agree there's 11 decks in the saucer, that is).
I can, however, envision maintenance personnel walking down those narrow hallways in the neck as they inspect and test service points on conduits, etc. So, basically, those areas would be strictly maintenance corridors. I'm sure the neck has service areas just like any other part of the ship.
The windows on either side of the neck? I don't have a clue. I'm convinced the placement of windows all over the ship was done without even giving thought to what areas are actually inside those windows.
I suppose the windows on the neck could be used by the maintenance crew to visually inspect the hulls. They could look down to see the top of the engineering hull, and look up to see the underside of the saucer. Then again, maybe not!