Hallways in my forts, especially high-traffic zones, are usually 3-wide; also to allow for wagons to have an alternative entrance.
Wavehandle is still one of the best examples I use. Having primary-designation zones also works very well, provided industry can work from it. From the same fort, I have a prison in front of my food stores (for processing and brewing and torture of prisoners), I also have livestock storage within the same zone close enough in proximity to the butcher/tanners. Much beef to go about the fortress.
I somewhat like to keep some sort of realism/plausibility throughout the fortress/project. Again, Wavehandle, as well as Bloodfist are examples. Wavehandle also having a sewer of sorts for constant water supply and such (no back door through here; you fall in, you deal with the carp.); as for Bloodfist, the ship is a mere skeleton still, and is being constructed in a sky/dry-dock.
You can say my design style is similar to my drawing style: realistic to an extent, but still loose enough to be fun and creative. Plus, if I'm not planning, you would notice parts where I truly wing it, and try to make something work. I also have a habit of making things modular so that I can easily modify, or cheaply build upon something.
Also much how I draw, I usually come up with a purpose, and then build the mechanics of it all, all this before I make it stylish; if it needs to be. But like above, I mostly wing it with my designs with as little precision/effort as possible. I apparently had tons of moods now that I look back at my sketchbook and forts.
Reference Maps:
WavehandleBloodfistI noticed. Project idea aside, I think what truly makes Bloodfist enough of a megaproject in itself is how I'm building it. It adds a challenging flair to it. Build the scaffolding and support structures and such before actually building the construction itself. Much like how archways have a process in building them, as well as wooden boats.