For the most efficient forts, don't use stairs. Use ramp corridors
Well, for the
most efficient forts, restrict all dwarves to one z-level. This is difficult in practice however.
I usually have my fort divided into a couple of sections. There's the bedrooms/diningroom/foodstorage area, which has the dining room right next to a food and drink stockpile with a brewer and cook right next to it to one side and large swathes of bedrooms on the other, along with a hospital/well and any barracks I need. There is the farm area, which has farms, a farmer's workshop and as many animals as I can fit in it. I usually need to keep more animals down in the caverns to prevent starving, and put another workshop down there for shearing purposes. Right outside the entrance I have a butcher/tanner and refuse stockpile and right inside I have a trade depot along with a bunch of craft/gem cutter workshops and a craft/clothing storage area. I usually put my other workshops between there and the bedrooms, unless there's a big z-level distance between the two for some reason. And finally I have a magma forge area, hopefully close to the rest of the fort but down in the caverns if necessary. If it is down there, then I have some food/bedrooms for the smiths set up as well.
I try to keep all my hallways 2 tiles wide, unless they're in a high traffic area in which case I make them 3 tiles wide. I don't leave unnecessary walls up, and I make my bedrooms 3x3 for normal citizens and 5x5 for nobles.
In my most recent fort I'm trying to build a set of large mid-air disks on which to house my dwarves, supplied with magma and water via pump-filled columns. Most of this isn't built yet, and none of the water/magma stuff will be set up until the end due to trouble in placing windmills. I intend divided it into four areas to make the best use of the water/magma. There are three smaller disks with one central one in the middle connecting them together.
One disk has all my farm workers and food preparers, with a few bedrooms for them, a few areas covered in grass for livestock if possible and a few covered in mud for farming. There will probably be a couple layered disks here with workers for that layer housed on one side of the disk. On top will be a bunch of windmills to power the pump stack for water when I need it.
The next disk has all of the workshops related to fortress-specific items, like furniture, mechanisms, that sort of thing. There isn't anything special about it, it just is there to not take up space on the central disk.
The last smaller disk has all the crafts and clothing makers on it, as well as a trade depot and the mayor's residence. It is the only disk with a direct connection to the ground, which is a spiral ramp which is designed to let caravans up. There will be a bunch of traps set up to stop intruders, along with some war-trained animals to stop any kobolds who get past the traps.
The central disk is the big one. There will be a mini-aquifer system to take extra water from the farm area, which will be piped over to fill in a small reservoir with a couple of wells around it and a fountain/mist generator in the center. There will be a small statue garden/courtyard area around the fountain, and a few dining areas around the courtyard. Some closed in, some open air for exposure to the waterfall. There will be a bunch of warehouses, a barracks which will house mostly marksdwarves, and a hospital near the wells. There will be bridges connecting it to the other disks, which will all be detachable in case of an emergency. There will be some apartment blocks, some nicer houses, and a small palace for the non-mayor nobles. Down underneath this disk is the forge area, with some magma piped up to it, along with a nice big mamga reservoir. There will be an emergency hatch to dump all the magma, as well as a pump to pull the magma up to the surface and spit it out through the fountain in case of emergencies.
My only regret about this is that the site I chose freezes up in the winter, which makes my fountain somewhat impermanent and dangerous. But the rest of the site's design is so awesome that I couldn't not go with it: there is a row of hills right under where I want to put the disks, which is a nice place to base the pillars I want to set them on, there's an aquifer for me to pull water from, and a volcano in the middle of one of the hills on which to build the central disk. Lots of mica, Plenty of soil, and right at the meeting point of three deserts and a savannah, so I've got plenty of sand and wood.
I'm hoping that by restricting workers to their disks, apart from some haulers to carry food and stuff around, I can avoid excessive fps trouble like I've had in past forts. Acquiring raw materials will be difficult though.