Was very excited for a second there. Not only was there a short spire (and several others nearby), but this was a 4x4 with serene, untamed, and sinister surroundings, flux, iron, 2nd-level magma, etc. It would have been perfect if not for my dwarves contracting spire syndrome. The spires were all open, but nobody seemed interested in coming out to play.
Interesting to note though that I had no utilities open when this world was genned. It was simply the fourth world in a series as I was tweaking rainfall and drainage variance/mesh size, as well as desired good/evil square count. Nothing on the embark screen indicated unusual topography or cliff size, although I thought it kind of weird that the serene marsh didn't have an aquifer.
Whether the map loads on embark seems random, and the FPS runs at about 30 (Normally I don't drop below 100 FPS until I hit 30 dwarves), but the circus seems to contain a hovering underground lake, so that probably had something to do with it.
My usual method for finding the best embark in a region tile is to load an 8x16, scout it with dfreveal, and pick a 5x5. Somehow this worked for this world, although the unusually long loading time was my first indication that something was odd. The areas adjacent to the 4x4 I picked had additional spires, none of them much taller than 20 levels above the surface, all of them open. There were magma pipes breaching and flooding the circus, which seemed to destroy my FPS even while paused. I chose the 4x4 that I did because it was the only place containing a spire that wasn't being inundated underground by magma. Was really hoping that it would let me mine...
*sigh*
When setting values for desired good/evil, I set each of the six values to 4000 and tried to gen a world. After several rejections with the message "Not enough entity placement locations" I lowered it to 2000. Not sure if this can be reproed with those steps, but that's the only thing I can think of that was different this time.
If you feel like trying to repro this, let me know if this reliably generates spire worlds for you, and if you can get one without the spire syndrome occurring.