I'm about to place an order for a custom size Big Mat, which I read about in Threads.
http://www.sewingemporium.com/
My husband made me a custom cutting surface that sits on top of my dining room table and brings it up to a comfortable height. It's much smaller than what you are considering, but larger than my current mat which is deteriorating. Before Christmas, I did a bunch of research on mats and between the 'it's stinky' and 'it doesn't self heal' reviews, I narrowed it down to 2. I ordered the 8X10 sizes in both and decided to go with the Big Mat.