My current fortress is built on a flat plain next to some hills, right next to a brook.
The entrance is a 3-wide set of ramps that goes down into a medium-length 3 wide hallway. The hallway then widens to a 9 wide room, where the trade depot is. Behind that room is another hallway with a set of down ramps onto level 2.
The trade-depot room is linked to the brook, and has a drain to the deepest Z level. (This is how you get around bringing an anvil at the beginning.) I kill all caravans unless I want migrants that year. I've even killed the few liaisons that dare venture my way.
Also on the upper level, behind the ramps to level 2, is the lever house. Its the mechanical center of the fortress, and the most defensible position.
Behind that is light industry, barracks, death pits, farming, and epic storage.
Level 2 is living quarters, meeting halls, and the grave-pools. I use a 4-to-a-room stateroom style living setup. A rounded 9x9 room with 4 beds, each defined as its own room with no overlap. In the center is a small dining room and food/drink cache. There is no big dining hall.
Level 3 is noble quarters. Royal rooms all around.
I've only got a magma pool, so heavy industry is in it own zone, not connected to the rest of the fort except by a stairway that goes directly into my ore storage. I've got 20 magma-powered workshops next to 5 staterooms, so every one of my metalworkers, engineers, furnace operators, glassmakers, and miners has a bedroom close to the action.
Below heavy industry is mining.
I've only got a magma pool, so heavy indu