What to put under swingset

[weepingwillow22]

We would like to get more year round use out of our swingset. It currently has grass/mud under it. What would people recomend as an alternative? Fake grass, bark, rubber or something else?

The rubber is quite rough and wood bark chip will rot. I hate fake grass, so I'd suggest the plastic that protects the grass but let's it grow through, so less mud. Here these type of thing are 3.49.

My friends replaced their rubber chips this summer with fake grass though. I think it's ok, not sure how slippery it is now it's dewy/ rainy.