Fred,
I don't know what kind of area you're in out there in Montana but out here in the East (where everything is acidic). Pine needles make a great mulch for this purpose. They take quite a while to break down, are comfortable under foot, allow water and air filtration, suppress weeds, and are free. I have a gardening friend who laughs herself silly because she bags up tons of pine needles and drives them over to me. I use them in my perennial beds, around my raspberries/blueberries and garden walkways. It's a win-win.
