I use astroturf. Two pieces, so that while one is being cleaned and hung to dry the other can go right back in the enclosure. I like it, it looks good and my Cali King seems to like it too. The only problem is that the astroturf frays on the edge after a while and if it's not flat them my snake will go under it to hide. When I lift up the turf to check on him or take him out, it spreads the aspen all over the enclosure. Oh well.
I also have a pile of aspen chips/shavings in one corner under the warm side hide so that he can be in the hide and choose if he wants to be right on the floor/heater or on the aspen so it's not so warm.
If there is anything the nonconformist hates worse than a conformist, it's another nonconformist who doesn't conform to the prevailing standard of nonconformity.