The next set of images demonstrates ambient occlusion with the PhysicalSurface root node. Observe, there is texture surface and shadow darkening, which is why I applied an HSV node to elevate texture brightness. Please note the point where the table intersects the ground plane, deeper shadows, simulating the area light doesn't reach. If you increase the Distance dial on the AO node, you should be able to extend the shadows.

Also note, any changes applied to the table were also applied to the ground plane.