Modular and neat, like goes next to like, always leave room to expand stockpiles / workshops as necessary, always try to avoid duplication of rooms. for example, on one floor I'll have food / drink production (farm, storage, kitchen, butchers, fishery, etc) and meeting hall. Next floor I'll have masons and carpentry and their needed supplies as a production level for furniture, etc, that's needed for my fort. Next level I'll have jewellers, craftsdwarf's workshop, cloth and leather, for what usually tends to be my main source of export. Next floor are my furnaces, smithy and engineering, where I'll keep seperate stockpiles for each stage of work so I can more easily assess my needs (lignite / coal stockpile next to smelter, next to coke stockpile. Two seperate metal ore stockpiles, one for valuable metal and one for functional, same for the metal bars produced. I'll also try to make workshops / stockpiles follow the same sort of pattern on each floor, looks neater and allows for little backdoor shortcuts for goods / materials that need moving between floors. I'm not usually this OCD in real life.
...Back in 40d when marksdwarfs worked I used to (and probably will do after the marksdwarfs get fixed)...
I've seen a few people saying this and haven't been playing the new release long enough I guess, what exactly is wrong with them? I haven't assigned all that many yet and haven't been sieged all that much, so haven't noticed anything out of the ordinary...