Jeebus! Look at all that empty space!
OK, well, I wouldn't call my current fortress a model of beauty, but I generally build with efficiency in mind.
The most important thing to remember when going for efficiency is that vertical travel costs as much as horizontal travel. When you build workshops in a row, every workshop must be spaced at least 3 spaces away from the last one. A row of 5 workshops is 15 tiles wide. A stack of five workshops built vertically on top of one another only takes 5 tiles of vertical movement to travel past.
This is what I do: On my main floor, I tend to just build very wide hallways that use diagonals if need be to connect all the stairwells. I section off my fortress horizontally - I build food production, clothing, and dining in one quarter (near the soil); trade warehouses, animal storage, butchery, leatherworks military, and wood industry goes in another quarter; Metal and magma (glass and gems) goes in another quarter, hopefully on top of sand; Stoneworkers and other misc goes in the final quarter. Housing should be shifted to be as close to central to the fort as possible, with everything else being like spokes off a wheel.
Preferably in a soil layer, just off the hub floor, I build the warehouse level(s). I like to build thick (like 2x2 or 1x2) stairwells that have walls orthoganal (non-diagonal) to the stairs, so that you have to travel diagonal to access a floor. That way, even if doors are stuck open, miasma is trapped on a given floor. With fortresses compartmentalized horizontally instead of vertically, that's even more advantageous.
Around these staircases, a large, square warehouse is built, with several one-tile stairs down (with walls on orthoganals). Below or above the warehouse floors, the stairs lead to rings of workplaces directly next to the stairs. They should be just far enough away from the stairs to allow for a door, for fey moods. No extra spaces.
I also used to simply make each floor in a stack have a smaller stockpile, with rows of workshops built directly off the stockpile, with the stockpile being a "hallway" of sorts, since junk stored in stockpiles doesn't block pathing. This means that if you don't care about cleanliness, you can technically make your stockpiles your highways or your highways your stockpiles.
(Good for storing surplus furniture if your masons go overboard, you can just (h)ide the furniture until you use it.)