I use hand quilting thread too, then I don't have to play with the bees wax circle thing. :shock:
My thought for quilting this would be to use a bigger hexagon as a template and quilt it over top the ones you did. But the suggestion about quilting every other hexagon sounds like a great idea and would be quite beautiful. As a bonus you wouldn't need to find/buy anything else. :)
It's already an amazing piece. :D