I've seen pictures of floorplans of several megayachts, and it seems that the crew quarters are usually toward the bow below the main deck (it explains some of those lower portals you see by the waterline). Given that some of the new Gigayachts are carrying 30 or more crew (say the Pelorus and Octopus) the crew area must be rather impressive in its own right.
Have any of you seen the crew quarters on large megayachts (>50m)? What are the provisions for dining room for the crew? Are there crew-only lounges?
I'd guess that having nicer crew quarters would allow the owner to be able to hire and retain a better crew.