We have kid-safe cedar chips -- and the "raised bed" containing them looks like the raised veggie bed we have. Not beautiful, but functional!

Our school playground across the street has plain old wood chips and they work great. They eventually break down which is good for when your kids outgrow it. Cheap and easy and surprisingly soft.
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We used redwood chips in a 16' x 24' perimeter of 4x4s (bolted together - 10' high) installed by the Playset Place in Lubbock, Texas.

The material and depth met the recommendations of the U.S. Consumer Product Safety Commission.

Here is a link that might be useful: Playset Place

We too used wood chips- triple shredded so they are soft and not splintery. I found a place that sold it (they called it playground fiber) in bulk. They delivered 10 yds to my house and that covered a 500 sq ft play area 6 inches deep.
I think they look good and smell great!
Here's a photo. This is the side of our house- an area we now call "the playground".