I started with my iPhone 4 footage and managed to get a solid 0.7159 solve error (using the phone preset w/k1+k2+focal length) with just 21 markers (including my new Favorite Thing, perspective markers). Huzzah!
Except when I Setup Tracking Scene - the presented solution shows the camera and the markers in an almost completely straight line, or has the camera stretched out to a ridiculous distance, covering the markers (which are in an almost completely straight line).
I've set the floor, the origin, the x axis, the scale - all to only minor adjustments.
How can I convince Blender that it's looking at a fairly broad street, not a tiny, thin path?