I haven't thought about it much, especially since this is only my third fort and I forget what happened to the other two buuuuuuuuut... some moments pop up.
First, when making the fort, I created a Vault which will contain ALL our valuable metals (Gold, Silver, etc.). The only way to it is two narrow passages lined with cage traps, and a war dog chained out front. Above it is the catacombs... the dead resting on the riches of the future.
Another thing I made was a Dwarven Bunker. The idea is that, when the traps out front are defeated and the military crushed, the surviving dwarves can run into the bunker and seal it off from the outside world. There's a well, 60 beds, emergency food and ale stores, and small stone and wood stockpiles. If they can't recover the fort, they can open the other entrance and escape, sealing the foe inside the fort to prevent it from terrorizing the countryside, and allowing a reclamation team to come back and recover the fort from the bunker.
Current plans involve making a Divine Quarter. Or Temple District. Or whatever you want to call it. A large empty square with temples to each of the Gods the dwarves worship around it, of which there are 8. Each temple has a unique and themed look, and has an icon for the god on the floor. Or it will, I drew up designs on graph paper and JUST finished that. Mining will start soon.
Future plans involve making mini-forts in portions of the caverns I found, or creating safe areas of those caverns. I have two areas I'm looking at, one of which will be hard, but profitable (Narrow and short passages in, but there's a flying slime FB in there, as well as one or two other FBs) and the other... well just for fun (It's pretty much barren and thus has no real use, but having a LONG, narrow arch of the cavern all of my own would be NEAT.). I may stockpile THEM with extra food and ale as well, just to keep them as backup safe zones.
There was also a moment that stood out a bit in my mind. A pair of goblin ambush parties appeared, one of them killing a child. The military went out and killed one squad, then I sent them back in. One dwarf though, a wrestler, was caught by the other ambush party. I tried to get him to run, but he didn't. I tried to get the military to go for him, but then realized... the goblins in the party were all running! All but one. I watched in amazement as the wrestler proceeded to beat the crap out of the goblin (Knocking out a tooth at one point), the goblin constantly trying to crawl away from him, before finally the goblin died. I imagined the dwarf was furious at the child (Not his I think) dying, and was taking it out on this goblin. Brutally.