Main burner for gas fireplace won't stay lit (pilot light is fine)
After dealing with the pilot working for periods of time, and then having trouble again sporadically, I finally ended up calling a repair tech to come out and look at it. His solution was to build a sort of "hood" or "shelter" out of thin sheet metal around the top, back and sides of the pilot light. 

It's been almost a year, and I have had no problems lighting the pilot, or keeping it lit since then. The working theory is that the pilot was essentially being blown out by the oxygen that was being pulled into the unit by the flames.