I second the plastic wrap comment. It's great for cold, winter days because it gets nice and warm for the sub, but you can still see everything.

As far as the kind of rope I use: I have a few different kinds. Every once in a while I make a trip to the hardware store and play around with the rope to test abrasiveness, or smoothness, and get something new according to what I need. I try not to get anything too rough, and I'm not so much a stickler for appearances that I'll sacrifice functionality and ease of use for a more aesthetically pleasing design. I tend to prefer either black or white rope (or brown, in the case of hemp). I also think that string is a valuable tool. I keep a spool of hemp string, and some other, softer strings as well.