Hi David,
I'm no orchid expert, but on my part, I would personally go for jewel orchids, like Ludisia and Anoectochilus as I understand they are adapted to grow under low light conditions, ie: forest floor. They have a special vein pattern structure and red colouration beneath the leaf to allow light that penetrates the leaf to be absorbed back into the spectrum. Jewel orchids are interesting in that they come in a variety of colours and shapes so you might want to consider growing them.
