You would probably be better off making your own from plain fabric. Then you can make them exactly the dimensions that you want and choose the right colors for the room. I would imagine that heavier fabrics that block out light would be better, but this could be a matter of personal preference.
Years ago I visited Yes! Hostel in Lisbon, and they told me about some of the challenges they had with their bed curtains. Guests would consistently grab the curtains to pull themselves upright when they woke up in the morning, frequently pulling down the cable that supported the curtains. They recommended using heavy steel cable that is firmly anchored in the bed instead of thinner wires. An actual curtain rod would probably take too much space and it might be used as a handle for guests climbing in and out of bed.