In my latest fort, I've implemented a design, based on the well-known mist generator.
advantages:
up-down ramps, power transfer to all 4 directions, compact, FPS-friendly, and modular. You can have mist generators on your main route every second floor.
downside: the tiles below the mist generator's channels cause some job cancellations (dangerous terrain).
Those are not very frequent though. They are so uncommon in fact, they don't bother me at all.
design's floor designations (with power coming from the north, and reservoir to fill the mist generators to the east, in this case):
z = 0
www._.www
www...www w = wall
w_.._.._w . = floor
w.......w ^ = up ramp
w..^wv..w v = down ramp
w_.^wv._w _ = channel
w..^wv..w + = constructed floor (prevent tree growth)
w.......w
w_.._.._w
wwwwwwwww
z = -1
www._.www
www...www
w+..+..+w
w.......w
w..v.^www
w+.v.^w+w
w..v.^www
w.......w
w+..+..+w
wwwwwwwww
design's buildings:
z = 0
www.G.www G = gear assembly
www.h.www h = horizontal axle
w_PPGPP.w PP = screwpump
wPG...GPw
wPh^wvhP
w_h^wvh_w
wPh^wvhPw
wPG...GPw
w_PP_PP_w
wwwwwwwww
z = -1
www.G.www
www...www
w+..+..+w
w.......w
w..v.^www
w+.v.^w+w
w..v.^www
w.......w
w+..+..+w
wwwwwwwww
Here's some pictures with variations of the design in my fortress:
The entrance. To the right of the centre, top, you can see part of my generator room. I am building a 70 z-level high magma pump stack, so it's rather.. large. To the right, the entrance, and the edge of the map. the pressure plates link to the bridges, dropping invaders who make it past the traps a comfortable 5 z-levels down to pain and misery. to the left, part of my tree farm. All muddied from a single small rainwater pond, with the help of some floodgates. Took 4 -5 years.
The level below that. The two lever rooms hold most of my fort's power, bridge and floodgate controls. I did not quite transfer power to the top mist generator efficiently, but have been too busy to rewire. Also houses the fort's dwarf-wash / swimming room.
The level below that. Dwarves chilling in the mist, in a small meeting area designed in the top ramp room.
Power is transferred south and then up, to the southern mist generator in the previous level.
A few more levels down, you can see the ramp room design combined with a small hospital (which actually functions quite well, the few patients with broken bones I had were treated and cured quite fast)
The level below the hospital is where I expand the design's use to four corners, creating that 'fortress' look fitting for the game's name.
In the center, my dining room, to the left, the living quarters. All rooms are far enough away from the workshops to have them dwarves sleep undisturbed by noise.
Further down, the transit floor. The four corner ramp rooms continue down to more living quarters, while the centre staircases go down to a new ramp room, which continues 70 z-levels down to the magma sea. The powerline is under construction, on it's way to power the magma pumps.