My mom had the discoloration problem in her old kitchen and bathroom, so I've always used rag rugs or oriental styles without backing. However, now that I have an active young cat, my rugs turn into piles in the corners. I considered trying that non-skid rug-backer stuff, but I'm not sure if it would discolor things or not.

Actually, I forgot and used standard bath rugs on our Armstrong vinyl in the bathroom, thinking the color is off-white and patterned enough that it might not show any discoloration; a year and a half later, so far so good. Is your flooring really light?

jessica,
The floor is a lighter tone, it looks like porcelein tile. My Mom won't use anything but rag rugs on hers, but those are slippery. The orientals are nice, but I would like something I can throw in the washer. I don't know about backer stuff either, most of that I think is latex or rubber. You would think they would sell more throw rugs for vinyl since its used so much.

WunderGrip markets rug underpads from Germany that I sell to my customers. Contact them and perhaps they can give you the name of a local rep.

Here is a link that might be useful: Wunder Grip