I just started a new fort in the 64bit DF. Akirmorul.
It's almost a perfect site; my bottomless pit of despair reached past the caverns and all the way to the magma sea without breaching the caverns, I have an organized work force despite not having Therapist (just took two hours going through the unit list painstakingly). Iron is in abundance under the desert sands, and I have Limestone... Steel production is a tree farm away. Glass (even clear glass) is not only possible, I've already set up the class furnaces down at the magma shops. The desert, surprisingly, has an aquifer beneath it, so water is in abundance as well. Even if that wasn't enough, the caverns are flooded as well (I run only one cavern layer for fps reasons, and I prefer them wide open because I like the looks).
Then I start getting migrant waves. The first wave was 2 adults with their 5 children. Next? 4 children. Next? 18 children. Next? 23 children. 50 children immigrated in a year. Nearly half my fortress' population. Unfortunately, the pit of despair is for elvesrapid pathing to the lowest reaches for the nobles. It's not designed to accommodate mass removal of citizens.
At least I have yemeni Wanalalolama, the craftsdwarf.
*Edit* Well that solves the problem of too many children. A goblin force arrived, and I ordered the gate shut. It was never connected to the lever. Cue 7 goblins gaining access to a mostly child-filled barracks. Lost 22 Dwarves, 14 of them children.
*Edit 2* Looks like they only had two military dwarves, and a miner and a doctor to contend with until I realized they were inside. Then they had the inferno of rage that is Zas, my commander. She practiced vivisection via axe on several goblins. She would have had more kills, but a macedwarf exploded the head of one, and a sworddwarf gutted the other. But for the most part, one dwarf dealt with the entire group. Then she went to pick plants out of the farm.
*Edit 3*
On a sad note, I found out that my 2nd squad's captain was married with and had 5 children with (they apparently were the ones from the first wave) one of the members of his squad. She was also badly wounded, and my chief medical dwarf was one of the dead civilians. So her prognosis is grim. All 5 of their children also died in the fight.
*Edit 4* And I'm back to having a large percentage of underage dwarves in my fortress. A migrant wave pushed me to 66 children, 143 total, despite my pop cap being set at 120. At least I rebuilt my military, then strengthened it, and have a medical corps again, even if they're completely untrained.