http://www.physicalc-software.com/tutorials/ao/

In those images at the above link that show examples of with and without AO, exactly what improvements am I looking to see?  TBH with the exception of no shadows in the "without" image, I don't see any difference in the quality of the render.  To me the "without" looks like it was rendered without shadows, and the "with" with cast shadows on.

"It is good to see ourselves as others see us. Try as we may, we are never
able to know ourselves fully as we are, especially the evil side of us.
This we can do only if we are not angry with our critics but will take in good
heart whatever they might have to say." - Ghandi