Both my father and my wife have disc herniations in their lower back, and have had plenty of pain to go with them. The mattress that they sleep on is probably the number one thing that makes their pain better or worse (apart from physical activities that aggravates it). They both much prefer firm mattresses to avoid having pain. Even one night on a soft bed will mess them up for days. My dad actually uses a wooden board under a thin futon mattress to sleep on. Yes, it give him some discomfort on pressure points at first, but he got used to that, and it's a lot better than back pain.

Wooden boards may be a little extreme for most people though. My wife and I got a memory foam bed a few years ago, and after the initial adjustment to feeling like you're sleeping in a body mold, her back does very well with it. We had to shell out almost $1k for it, but it was worth every penny. I hope that might help some.