Woah! I for some reason didn't get notifications for any of the above comments. Ha. I don't have much to add to the discussion regarding whether or not that space is easily accessible (or accessible at all, for that matter) on either the TOS Enterprise or the Refit, however the Refit definitely has the advantage of having the deck above the flight deck.
I haven't modeled out the cylindrical structure above the hangar doors on my internal hangar set yet, but will be doing so when I get to refining the clamshell doors. Over the weekend I focused on refining and texturing the internals of the flight deck itself and did some preliminary lighting work. Still have to refine/texture the large structure in the middle of the ceiling (which I will be modeling as a tractor beam emplacement, much like what is depicted in FJ's work), the pocket alcoves, the floor, and the clamshell doors. Once those are completed, I will move on modeling the spaces in between the pocket alcoves (unseen on camera) which will most likely contain ladder-ways into the control booths/observation deck. I will also investigate whether or not a control room actually can exist up there above the doors at the scale I've modeled the flight deck (to scale to the filmining miniature of the flight deck, which is the same size as depicted in the MJ illustrations of the flight deck in TMoST), although I'm pretty doubtful, and there's still the issue of how to access that area anyway. I mainly want to investigate to satisfy the curiosity of myself and those on this forum
As far as the "Elevators" and "Warning Fire" text that are in the alcoves, I will most likely be changing this text to say other things, since we never see this text on-screen and only on behind-the-scenes images of the model.
After the flight deck is completed, I'll move on to the hangar deck which is theoretically below the flight deck, and whatever cargo complex I come up with will be located just forward of the entire flight deck/hangar deck complex.
Anyway, here's a shot of where things stand currently. Lighting is currently WIP and wonky in places (I've never lit an area this big before in Unreal!). Textures appear pretty smooth, but when you get up close and the light hits just right, you can see imperfections and some light dirt/scratches. You'll also noticed that I kept the exterior of the observation deck/control booth windows as opaque emissive panels (like they were in the show). My thought is that they're emissive/opaque on the outside, but non-emissive/transparent on the inside. Some 23rd century tech we're not familiar with in the 21st century

One of the other reasons I've made kept them opaque from the flight deck is because I will have to hide the observation deck geometry whenever the exterior of the ship is being rendered because there's no way to fit the interior of the observation deck as it appears on-screen into the exterior hull of the ship, even at 1080'.
