....
Mine tend to be "small foyer on the ground level, leading up into the giant anvil shaped structure in the sky"
My fortresses tend to be LandTanics, and tend to "sink" mysteriously after an unfortunate ccidents where the bulkheads fill with magma, destroying the mechanisms inside the vertical supports.
OT, I know... but...
What exactly does a rooster feel sorry for doing that it must undergo catharsis to feel better?
Back OT:
The secret is as others have said, maximum efficiency, and reduction of wasted movement within the fortress.
Think about what industries your site offers, and tailor your fortress accordingly.
Is it high in mineral wealth? (Jewels, metals?)-- does it have a surplus of underground soil to exploit for a booming fabric industry? Is that soil sand or clay? Are you going to do a glass or ceramics industry?
Think about what your fortress is going to be spending the majority of its time doing, what is imports and exports will be, and then plan workstation and housing arrangements accordingly to maximize production flow.
Remember that access above and below the current level is "faster" than access within the same z level, so having towers and shafts for product flow is to your advantage.
Here's a hypothetical example:
Here we have a dedicated clothing industrial pod, adjacent to a glasswork pod.
It is presumed that this is an underground soil layer, and that it is sand.
(Z0)
O==================O
|^^^^^^^^^#|.. .. .|
|^^^^^^^^^#|.. . . |
|^^^^^^^^^#|.. . ..|
|.. . X. .| .. X..|
|##########|#######|
|##########|#######|
O==================O
On the left, we have a farm plot (^^ chars), and beside it a barrel forbidden seed stockpile (#), which accepts ONLY the seed type used by that farm plot, which is dedicated to growing cloth for bags.
Southward of the growing tiles is a "quick harvest dropoff" food stockpile that accepts ONLY that kind of raw plant. (In this case, pigtails.) It forbids barrels, and forbids milled goods or prepared meals. ONLY raw pigtails. There is an updown staircase connecting this unit with the rest of the production chain.
On the right, we have naked sand (. .. ..), which has a sand collection zone over it, and a furniture stockpile that accepts ONLY bags and sandbags. It also has an updown stair.
Since magma tends to be "deeper", unless you have run special plumbing, the next layer in the chain is downward.
(Z-1)
O===================O
| CCC..LLL|GGGgggGGG|
| CCC..LLL|GGGgggGGG|
| CCC..LLL|GGGgggGGG|
|.. . XFFF|. ..X.. .|
|#####.FFFD#########|
|#####.FFF|#########|
O==================O
here we have a clothier, (C), a Loom (L), and a farmer's workshop(F), with a combination overflow custom stockpile that accepts pigtail cloth, pigtail thread, and finished bags, but NOT sandbags.
There is a door allowing access to the pod at the right. (D)
The pod at the right has 3 glassworks shops, (G and g), a stockpile for raw greenglass gems,
And access to the upstairs to get sand and to store overflow bags.
Next, we skip the pod on the left, because we don't need it-- or replace it with some other production line, such as stone crafts, adjacent to a magma reactor room, since the next level is presumed to have magma in it.
(Z-2)
O=============O
|MMMMMMMMMMMMMO
|MMMMMMMMMMMMM ->to magma plumbing..
|MMMMMMMMMMMMMO
O=============O
|######X#####.|
|############.|
|############.|
O=============O
We have some additional overflow stockpiles for raw greenglass gems in here, and well contained magma chamber to power the glassworks above.
In the layer below, you have jewler shops that cut the greenglass, and some the encrust the gems onto "something". That "something" could be stone crafts, fed from a rock craftsdwarf's pod above, fed by a magma reactor, so it always has stone to work with close at hand.
You get the idea.