Hi there. I use woodchips with no problem (aspen), as do many folks. However, if your snake is a hatchling, the reason so many people decide on paper towels is that it is easier to see the snakes poo or any regurgitated meals in case there are any problems (also easy to clean). I think problems from wood chips are more likely if you feed the snake on the substrate (although some people have said they think their snake ingested the chips from burrowing, but I think that is more rare).
The astroturf idea also works but I have read it needs a little more upkeeping as moisture can cause bacteria buildup underneath it. For my new hatchlings, I am going to use paper towels or newspaper until they are a bit bigger, then I'll move them up to wood chips (it is easier to spot clean too, just scoop it up and out).
Another couple options are CareFresh or Cell Absorb found at some pet stores. I even read someone on here that uses alfalfa pellets (like for gerbels/rabbits). If you do a search on "substrate" on here you'll pull up many peoples thoughts/reviews. Cheers.