My forts so far have displayed organic development. I plan a few things, and then it grows so I plan some more, et cetera. Mixed in with that are some highly spiffy symmetrical constructions, like my housing complex, but on the whole it's highly chaotic.
Might try a rigidly fractal one next time though.
Probably comes close to what I do...
Aside from building with the land, and generally not wanting to disturb the general geography as I build my fortress as an almost entirely unseen subterranean ediface, aside from a sprinkling of windmills, a drawbridge, and a ditch to pull water from stagnant pools, I also generally try to map out where my different districts go...
But I always wind up deciding that I really wanted FIVE magma glass furnaces, instead of three, so now I have to dig another magma channel to feed some more. And while I'm at it, I might as well get some more forges of other types, as well, since that way, I can segregate my forges by high skill job and low skill job as well as by what skill will be allowed to be used on that given furnace. And even though I put my windmills in a nice line, it turns out that I'm now producing more longland grass than three millstones are sufficient for, so let's add a couple more of those... And I keep running out of rope reed or pig tails, so let's make more farmland... (What do you mean run less of your clothier shops? Produce less goods for sale? What are you, an elf?)
It generally becomes a challenge for me to find a way to cram more and more and more of everything within my ever-more-crowded pre-planned districts.
In a way, it may actually wind up resembling a real city more that way...