I tend to separate my building styles out by Z-level. It doesn't always work out that way, but the fort I like very much and spend most of my time on has this layout:
-Farms on the first underground layer, laid out in a very organic manner. Also, clothiers and the corresponding stockpiles.
-Same deal on the next one down, except less of a warren (far fewer random passageways connecting everything, much more dependent on large hallways)
-Two very Roman levels of bedrooms. Straight lines and symmetry everywhere! Rooms are uniform, save for the starting seven, which are larger and engraved.
-The fun levels, wherein I dug artful catacombs, winding passageways, and multi-layer beehives out of the rock. Any ore discovered here is dug out in its entirety and the resulting passageway is turned into something.
-At the very bottom, some very convoluted noble bedrooms. They look like spaceships, only full of +diorite crown+s.
When a dwarf hits legendary, I take off all his cleaning/hauling labors...except burial.
I like to build little cafes all over the place as well. Decentralized dining just
works.
My military is usually completely cut off from the rest of the fort... either aboveground or tucked away in a catacomb somewhere. I don't like them mingling.