quick question on ground covering

We have a mud pit in front of the barn. DH is at a landscaping place right now. They are recommending something called granite sand to put down which is a fine gravel. Anyone familiar with this? We also have a 60x60 enclosure for the girls now to keep them out of the pasture (prego's remember) that we used roundup on the grass. I want something down there too to keep the grass from growing back right away and to keep it from becoming a mud pit. They are recommending mulch. I thought straw, but they said it would be too expensive. Any thoughts? Experiences?
Thanks,
Kristen