@kjw97 and @anon20961960 asked for experience with the glass chair mat. It’s great! I waited for a 20% off coupon and bought the Vitrazza mat pictured above (post #1).
Plastic mats tend to develop dents from the weight of the chair wheels, but there is of course none of that with the glass mat. The office chair glides smoothly now. As @webwalrus suggested, err on a larger rather than smaller size to prevent the chair wheels from rolling off.
My office space appearance is much improved. Discoloration of the old plastic mat caused my office-sized area rug look old and dingy. The new glass mat makes the underlying carpet look new again. I opted for the “Luminoso” or extra-clear low-iron option despite the extra cost.
Patience is advised. If you provide an email address to Vitrazza well in advance of your purchase, you may receive promotional offers. There were 20% off coupon codes just before Mother’s Day and Cinco de Mayo.