I'm going to write a shell script or a C++ program which creates planar graphs,
pipes them to my graph coloring program and lists successes and failures.

After consulting the internet I found only three reasonable candidates for planar graph generators.
Brendon McKay's plantri and fullgen
Ledas graph_gen
and Donald Knuth's Stanford Graph Base gb_plane .

Any thoughts on which planar graph generator to use, or anything?