Aside a pretty big airship, I made a rather epic dining hall (WaveHandle, 40d), and as of now, I am working on my own version of a Vault-Tec vault. A few parts are inspired by a Wastelands LP (PlumpHelmetPunk's), but I am not playing it in the Wastelands mod. It's more for re-learning the game (been a long time since I last played DF), and also learning 31.25 and onward.
I'm updating my fort's story as you would read a log in Fallout (1-3) and based on time-logged holotapes according to when they were found. Depending on how this place ends, they could have been either recovered from the ruins, or enshrined somewhere being read by a child generations ahead of time, or as a lesson of it's society's origins.
As you'll read from first year onward, it starts off basic and optimistic as a log, and quickly into a disappointment for being fooled into living in a total shithole. It is meant to be read in numerical order. I don't think I'll be making it a succession or community fort though. A bit much work I'll be saving for Bloodaxe later on. I'll just keep updating it in DFMA, and wait for comments if any. If anything, I'm just having fun adding a backstory to the fort as I work on it just to keep me interested.
Relevant Links:
http://mkv25.net/dfma/map-10595-galleygolds (My DF Vault-Tec Fort: Vault-221 (South-East US, somewhere in Atlanta, GA so to say. Provided I got the Vault numbering correct)
http://mkv25.net/dfma/map-5573-wavehandle (Epic Dining Hall)
http://youtu.be/T0LT4b0v0PM (PHP's Fallout Chronicles II Wastelands DF LP (Fort Mode))