I typically do a 5x5 column, then put storage around it for common items (booze, furniture, mechanisms, specialty food, booze).
Corridors go at angles away from it.
I used to do all kinds of ramp tricks in my central stair, to quicken diagonal vertical movement, but that hurt FPS. I'd rather keep decent FPS than save my dorfs 10 steps.
My favorite trick had no stairs, but rather had criss-crossed diagonal ramps connecting diagonal corridors on every level, then putting floor hatches over the ramp so it could be walked across on the same level. Was awesome for the dorfs, they could get from anywhere in the fort to anywhere else with nearly a direct straight line across z-levels, but the combination of ramps with floorhatches always opening and closing KILLED my fps.
I wish we could give a special "highway" designation, which was always assumed passable and blockages never caused re-pathing. It would be a simple change in code, and could have enormous benefits when used correctly (and disastrous when incorrectly).
The high-traffic designation does do that, so re-pathing still occurs.
I would absolutely take on writing optimization for pathing, if Toady threw the pathfinding related source code at me.