This is what happens after you stop caring for cleaniness.
Sweet Armok-- I've never seen such a horrifying thing in my life. I regularly have 120+ population forts, I've let some climb to over 200. My pop cap is 120, with a child cap of 50. This still results in populations getting into the 150 range. My advice is:
* Think bigger. The Wiki 'can' and people here 'have' pointed out some mega projects.
* Don't 'over turtle' your fort. Forbid crossbows. Make your own challenges.
* Start collecting (and taming) mega beasts and exotic critters. Fill that moat with cave crocodiles and laugh as you dump goblins in.
* Get your endgame production chains going. Steel, Admantine, Soap, Crystal Glass... And replace everything you can with that stuff or precious metals, and encrust it all with gems.
* Pick one aspect of the game you're not familiar with and explore it thoroughly. Not sure about Ballista? Make them your primary defence...
* HFS
* Aspire to be 100% self contained including trees.
* Use a mod, or beef up the raws (Size / Damblock) on all Megabeasts, Semi-megas, Demons and large monsters... I find giving every one of the above 1.5 Size, and if they have Damblock 1.5 Damblock (or a small flat Damblock if they don't ie- 3 to 5) helps with the excitement level.
I generally try to do one of each of the above on each fort I make, then abandon...
General notes on the economy:
* Never make coins. Work on credit.
* Pre-economy 'better is better' for individuals, post economy 'worse is better' for individuals except for common areas (dining rooms, etc) and public housing (build glorious barracks). You're going to want an even'ish' split between bad, OK, and good rooms for all of your Dwarves, with a bias toward 'bad'. The good rooms should get assigned to your champions and be taken off the market for the most part. Getting the rooms right isn't too tedious because when you start resources are scarce and produced goods will be of generally worse quality. So just resist the urge to smooth, expand, or otherwise renovate your housing as you build, and just build better as you grow. That'll reduce evictions, and if dwarves do get evicted they'll sleep in your glorious barracks so they'll be OK. Oh, and build shops.