I hate it when I overlook the obvious!
I moved autogen to dense, and lo and behold, there was more detail -- imagine! I had read somewhere that "Normal" settings in P3D are higher than those in FSX, so I left the stock setting.
I did notice that the stock bgls in /Scenery/NAME for New York are different in size: FSX is about double the size as P3D. Wonder what that's about?