Bunk bed and desk - something like this
? An interesting idea (in a suitably TOSified design of course) and solves the problem of both a work area and
a roommate (plus an explanation of the extraneous door)
An open bathroom & closet room is a good option - the (opaque) mesh could be the edge of a sliding door that closes off for privacy.
However, I am much more spartan in my view of Enterprise living conditions and see no reason why everyone should get a personal bathroom, or even their own room. Yes they'd have to do the 23rd century equivalent of hanging a tie on the doorhandle when having a "friend" over and as Mario_de_Monti
said this is a lot like a college student - but time and again (especially in Season 1) we see the male crewmembers acting
like college students, so what's the problem?
The idea of everyone having their own room is lovely, but the biggest obstacle IMO is that its already been done - by Franz Joseph. Following Roddenberry's instructions in "The Making of Star Trek", FJ allocated a single bed to each of the 430 crewmembers (those sharing still had two rooms, so the ratio of each person having their own room still applies) The result: is deck after deck of bedrooms. Now, this is not
a slight against FJ and I do not wish to derail the thread, but the fact remains that giving each crewmember their own private bedroom eats up a huge percentage of the Enterprise's interior volume, with very little space left for work areas and machinery.
Hence: cram them in, I say!!!
I don't know if I ever mentioned any of them before, but I've come up with very similar theories as Robert_Comsol
with regards to Uhura's cabin being one of the few with a bathroom, public washrooms being the norm (as per Kirk's stroll) and even corridors having different widths throughout the ship. As I mentioned above, I think my interpretation of wash areas is a little stricter, but in parts of the ship solely devoted to accomodation (or just low foot traffic) why would corridors need to be wider than 4 feet?