Several changes which I believe make it better overall:

• I removed the right side panel from the mesh: it will be re-added as a separate object so you can decided if you want panels, bars, or both.
• The “tile” section on the second 1/3rd of the floor is now raised slightly rather than recessed, which looks cool but also will allow to make it invisible (I only had black marble tiles for testing).
• The wall corners are beveled to make the 90° transitions softer.
• The ceiling has a recess for lighting.
• The ceiling now extends (down) all the way to the beam that runs along the wall and is also beveled in all corners.
• The baseboards will be hide-able too.

I started texturing the metal beams with a very small normal map, it almost looks good enough under the right lighting but I need something more…

(Sorry for the ‘dark’ the in-world test pictures are, I didn’t realize that when I took them)