Good luck with this. Sketchup does not handle large files well, I would recommend breaking your decks out as separate files for the detail work and just having a master file for cutaway views.
Actually, I have each deck separated into multiple layers. Sketchup does an excellent job of culling when decks are not visible and even on my P4 with 3GB of ram, it is *very* responsive.
Here's an update. 4th Deck (Hangar bay 1/Upper Phaser bank)
This actually has the 3rd deck added and the associated truboshaft network. The turboshafts are actually on a separate layer so you can render that without the ship. Here's the turboshaft network for the first 4 decks.
Here is the actual deck 4 with some of the rooms extruded into 3D space. I placed a shuttlecraft next to a maintenance hangar so you can get a sense of scale. Here the hangar doors are 3.5 meters tall. The actual hangar bay is quite large standing in at about 3 decks high.
Here is a shot of the ceiling of the hangar bay (Floor removed for clarity)
(sorry, the pictures are a little big)