http://www.shopsmith.com/ownersite/proj_articles/placesetting/
I rotated each ring 45* with respect to the ring below it. This is good since the ring seams do not line up, and the bowl has a more wild, interesting pattern.
I am not good at turning feet on bowls, since I do not have a very good chucking system on my lathe, and don't get much practice with turning feet. Instead, once I cut the bowl off the lathe (or remove it from the drive plate), I just sand the bottom flat, and add some felt to cover the surface.