Mark,

For rendering, I use Flamingo, that is a plugin for my Rhino 3.0. It is a relatively rudimentary tool as renderers go, but a notch above the built-in renderer in Rhino, and the biggest advantage is that I can just copy a model in MoI, paste it into Rhino and get it rendered presto. No file saving, no export, no conversion. Just plain workflow.

For more serious rendering, I export my model to Luxology Modo. I hasten to admit that I do not fully master that beast, by far. Even lighting and displaying a simple scene seems to be soooo awkward. I suppose that I am a bit dense, as it seems that others can get wonders out of Modo, but when I read their description of how they did it, I do not even understand much of it, let alone replicate it. How frustrating! In fact, I sort of like Modo, but I wonder why. Joke apart, I just cannot get myself in the mood of subD modelling, but if I did, I am sure that Modo is a great tool.