My current project, Siegetorch, has 50 dwarves, which was what I got to in just about a year of playtime. Three immigrant waves in the first year and a half or so.
I am working on making a massive Microcline wall, I already have a drawbridge and a moat that is 4 or 5 levels of open space and then magma at the bottom.
I am still working on a way to access the magma for industrial use, and I have barely managed to breach the brook, which I did in an emergency alcohol crCIA to stop my dwarves from dying of thirst. I now have an insanely deep well, and if a dwarf somehow survives the fall he can get out.
I enjoy the map because literally everything has to come across the same land bridge, past the same cliff, through the same wide area bordered by cliffs(this valley is where I was getting my wood until I realised that there were no more trees), and finally up to my wall/towers/drawbridge/moat.