After 12 years my Olfa cutting mat finally got retired. Initially I replaced it with a Fiskars. Took that one back after about 2 weeks. I'm not real heavy-handed with my rotary wheel, but every time I cut, layers of the mat would peel off. JoAnn's took it back without my receipt and allowed me to put the money towards another Olfa mat. I like the 24 X 36 size.
If you're not in a big hurry to buy one, wait until you have a 50% off coupon for JoAnn's or they put all of their cutting mats and rotary cutting stuff on sale for 50% off. I hardly ever pay full price there.