We are having some major landscaping of the area you can see in this photo. Originally, we were going to pave the driveway, but decided against it for many reasons, including possible damage to the two trees. Would it be best to a) have only the existing gravel between the trees, b) put in "turf pavers" (concrete squares with holes for grass), or c) something else? There will be a boulder wall where the boulders on the left are shown running from the bottom left corner of the photo running along the photo's edge up to the upper gravel driveway.

I'm in the Champlain Valley of northern NY.