Well I tried this, but I think I'm going to start over. 4 levels of dirt in a rocky wasteland really makes the mining slow. I did have clay however.
Here's some screenshots:
-1 z level from the wagon's spot. I've only managed to start to channel out one z level. Though I have a pit down to check for stone. Made four supports for the 'castle/tower/thing' as well as five kilns to keep clay production up for building while the miners go at it.
Main z level, 1 up from the ground level of the to be spire. Dorms to the left, food stockpiling, poultry and food workshops to the right.
Next level up(+1z) I have a hospital to the left, and barracks/archery to the right, with fortifications to shoot from(maybe). Thinking about putting a stockpile in the middle there. Maybe weapons, armor and ammo for now.
Top floor at the moment. Still under construction. Possibly a furniture stockpile if I keep going.
My issues with this fort come from it being rather large, a 4x4 embark, and completely flat. I have only 16Z levels above that it lets me go(might expand as I get higher? but I doubt it. Not sure how that works). And with so much soil to dig through it makes for mining very difficult. This has taken me 3 years. I have 7 legendary miners from the first group, and the first migrant wave of 4 is making good progress. But we don't have any sort of dining hall, and I'm lucky that the only dangerous thing I've gotten attacking has been a bunch of camels. granted, I've only got 27 dwarves, as channeling in dirt and building in clay really kills the value of things making migrants less enthused to join.
when I restart, think I might try and get a 3x3 around a volcano, and just channel down the sides of the magma. So when I decide to destroy it, I can unleash hot fury.
Not going to abandon this, it's just really slow, so going to try in another world.