As usual, I will eagerly hop on board for a good heresy.
If you've ever been aboard a working (wet) ship, you'll know that deck plans, accurate or not, can't capture the semi-organized cluttered chaos involved. A passageway might be two meters wide on paper; in reality one side of it is lined with storage bins stacked two- and three-high, with a few odd bits of equipment on top of those. And in what's left of that corridor, there's a pipe that runs out of the floor and into the wall placed in exactly the right place to trip you, and a wiring duct that crosses the ceiling at just the height required to give a running tall person a concussion. The engine room might look like a big space with a well-defined blob of machinery in the middle on the deck plan; it's actually a three-dimensional maze of narrow passages, ladders, access panels hiding little tunnels into the guts of the machinery, and so on and on.
I really like Douglas's idea of a flow chart and descriptions of the aspects of the spaces that will actually matter for combat (or getting through them in the dark, in zero gee, in vacuum, or some combination of these, or whatever other evil emerges from the GM's fevered brain).
On a working ship at anything less than an Iain Banks level of technology, space is *always* at a premium. You'll seldom be able to walk five feet in a straight line without bumping into something. On big high-class passenger liners, passenger spaces (especially common areas) *may* be a partial exception -- but even those will be smaller and more cluttered than an equivalent facility in a groundside hotel.