I do love the idea of a resin bonded stone layer, and it was my first thought, however, I have been told by three paving / driveway 'Experts' that eventually it will go green, because it allows algae to grow, and being a porous layer, the algae can't be shifted easily. It does however look stunning when done. I've seen exposed aggregate done, and it looks just as good, especially with a wet concrete sealer applied. From what I am aware, resin pathways/drives are not really a DIY proposition, requiring specialised equipment.