Okay, a brief update...
I've left the secondary hull alone for the moment, because I've decided to implement separation, and that means I'm going to be saving two copies of this model, deleting lots of features from each copy, and modifying a number of other ones... but keeping certain geometry (almost exclusively dorsal-related) to ensure that the two ship halves fit together properly (since they'll effectively, be made from the same data). In fact, if you look very carefully in the following images, you can make out the separation line.
Anyway, I've spent a bit of time this evening polishing off details on the primary hull exterior. I've got most everything on the topside covered (though there are still a few items... the twin red lines going from C-deck to the dorsal cap and the small red and green running lights). I've created datum curves for all the underside details but just haven't created the physical details yet, so they don't show up in renders. I haven't done anything along the saucer edge yet (except for the fwd scanners... aka "Nomad"), but that will be pretty straightforward. I have completed the "sensor portholes" on the underside, which was more complicated than I'd expected to to the complex curvature in that region. But before the weekend is out, I'll have the primary hull exterior details complete and will have "divorced" it from the secondary hull. Only internal layout (which, except where there are windows to look in through, will consist purely of laying out lift shafts and wall structures) will remain.
I haven't got the dorsal 100% done... internal wall structures (and bracing?) is absent, and of course there's no turbolift shaft yet. But I've got the major spaces completed. Look closely, below, and you'll notice that the windows there are, of course, really "windows." I haven't done the "sensor portholes" here yet, but there are only a few of those on the dorsal, so that should be pretty painless. You should also be able to make out the separation line... currently just a groove in the surface but shortly becoming a real separation between two models.
Zooming in a bit more, you'll recognize the largest "lounge" in the dorsal.
And here's that space, viewed from the inside (as far aft as you can get, facing forward). The ceiling in this space is 8' from the deck, by the way. Not a huge space, but certainly a great place for a "viewing lounge," I think...
EDIT: I forgot to put this in... it's not really showing much new (except for the impulse deck)... but it's a good illustration of the interaction between the landing bay (I call the deck below that, where the shuttles are stored, the "hangar deck"... to be consistent with real naval terminology) and the nacelle pylon structure.