Tricks with Worldgen
 Pave the streets with Adamantine
Adamantine spires reach at least up to the magma sea and no further than the lowest cavern so if you have three caverns then you want to set the levels below layer 5 to something large 100 being the max (this will give you 100 level spires embedded in complete layers of semi molten rock). Then for a possible bonus set levels below layer 4 to something large and the spires may or may not extend up into those layers. Using this technique i've had 4x4 embarks with 10k+ adamantine. Which is more than you could ever use. Sarudak
 Tricks with PerfectWorldDFTool
 Sedimentary Volcanoes
Setting the noise controls for weight, feature and smoothness very high will result in very large amounts of Volcano-sites, right next to large tracks of Sedimentary land.