I'm not an inside grower and with so many plants I don't get to experiment much. From what I have seen, orchids will grow on just about anything. As long as the required light, water and fertilizer are provided. What works for you may not work for me with my watering regime.
But, I have orchids growing on everything from driftwood(freshwater) to a cedar shingle.
I have an orchid growing on a crumbled concrete slab and I heard of someone growing in a bunch of broken up AOL CD's. I personally like that one.