This rules

Of those, I'm thinking as much as 40% are support staff. Little more than 5k active duty crew involved in direct operations.

~8000 feels a tad small for that much ship, but considering the sheer size of the vessel's crew, the lack of negative space in the design, and essentially housing a mobile city, I figure it tracks. There WOULD be a lot of unused space until, say, they required it, i.e. guest quarters.

For sure, and honestly, been looking at apartments, too! I'm seeing amenities aboardship feel like (just eyeballing mind you) they're coming in at about 2-3x the quarters' space.

I want that luxury liner feel mixed in with something that feels like a multirole vessel, something that communicates the idea that "these people might literally not leave the ship for years"

That and

6000 beings feels QUITE small for a 5 km by 4.5 km by 800 meter ship

But considering they range from 160 feet to a pair of inches, and I want somewhat fair distributions, a conservatory, libraries, halls, a massive hangar, I figure they'd need wider, open spaces.

You know I was just looking up a US Seawolf and the CVN-65 Enterprise, and a couple of cruise ships. Naturally the latter have far more passenger space, something that roughly feels more like 20-50%. The military stuff is intriguing, but I'm already operating on a "no bunks, tons of amenties" case

Oh he is, he's the Captain, and not even the largest!

Oh I love being a GIANT~

And going to your giant sized stores and errands. Don't worry, you're coming along as my assistant <3

Antennae, sensory organs...an enveloping gelatinous structure, like a ctenophore's membranes, a heavier form of shield...or a resonating membrane for omni-directional energy emissions...

My MAIN issue is how to tweak or innovate on this biology beyond fins, tentacles, the usual structures...

I want to try and think up new ways for this biology to function. Ramjet collectors that double as particulate collectors, similar to metabolizing free-floating carbon.

That billowing Predator-maw with another monster in that glowing bulb that flare once enveloped~

It's a great visual for me~

Exactly! I figure one way they evade missiles is literally attempting to telekinetically shift them off target, or to interfere with organic pilots or command staff within range, project hallucinations. This is combatted by an increase in simulated, visceral stimuli that's harder to replicate.

Snazzy, a little terrifying, the interior being bioluminescent, the exterior lightly-scaled, iridescent, scattering black when engines aren't firing~

passive-scan.*

That's part of what I'm thinking, it'd be too exposed. Sensors, and/or ECM/psychic warfare capabilities seem like the next step, and shouldn't be limited to designs that literally replicate their forms.

I'd envision this as a multirole, single-being craft; able to function as a low-power scout or probe, reconnaissance fighter, and small gunship, designed to consume smaller craft it comes upon, and flee larger craft with information. The lateral sensors are large for a pronounced, passive-scale.

The bulbous "head" would contain jetlike thrusters, FTL fins added to the head, lateral sensors. Out of combat or processing, the flare would "umbrella" around the cockpit; its emitters might be able to channel engine plasma for increased straightline speed, folding in near the body.