Marc brought up a good point in his thread on his latest osage bow. He mentioned wanting to get certain rings for the belly of his bow. I think we sometimes only consider what ring we want for our back, something reasonably thick that we can feel comfortable chasing and will provide good tension work. But you really might want to also envision what rings are going to be showing up on the belly of the bow as well. You'll have to estimate the thickness of the limb, that can only be done based on experience but you can usually get kind of close.
Lots of spring wood near the surface on the belly, is a bad deal. You want a nice thick ring on the belly, or at least thinner rings with good summer ratios. I kind of favor the slightly thinner rings though, just because the stairstep feathering of the rings is a great guidepost for doing the thickness taper.