I've used darkrooms with both a dedicated safelight (in a closet set up) and a group safelight (such as a gang darkroom). This set up will be a mix of the two. I have been using my Thomas Duplex safelight set in the middle of the room for 90% of the illumination, with the last 10% coming from a incandescent style safelight mounted above each enlarger.
I can't recommend the thomas duplex safelight enough. Its so bright, but has a slow fog time compared to every other safelight I've tried. It's light output is also adjustable. The downsides are a 120$ replacement bulb and a 10 min (or so) warm up time until its bright enough to work under.
The plans are missing where electric sockets, plumbing, and ventilation will be which contributes a huge amount to darkroom usability.