I have had a RadTech fabric sleeve for both my MacAirs and I just bought one for my PW2. It doesn't have any padding but does protect the device from scratches when it's in my bag.
http://www.radtech.us/products/sleev...le-sleeve-case
When I need more cushioning, I use the Dockem sleeve that Dr. Drib provided the link to. I bought the PW2 because it was small and light and I just can't see doubling its weight with some of the cases that are available.