Anyone know of a good way to equalize the scale of UV elements in Max, so that each UV "island" takes up space based upon how much surface area it covers? I know that flatten mapping will do this, but I'd like to do it with things that are already mapped.

If you "Pack UVs" it will scale them to minimize unused space. But I think it bases the new scale off the scale you already had... I'm not sure of any "automatic" way to to do equalize the scale. Actually now that I think about it, you can use the UVW Map modifier instead of the UVW Unwrap modifier. This will give better control over the size of the unwrap gizmo, which might let you set a standard size.

What I end up doing is, applying a checker pattern and making the squares roughly the same size. I also choose to scale up important detail areas and scale down others that are less important.

Using the relax tool on all of your uvs at once should scale them all to be the correct size relative to each other. Might not be the best idea if you already have the uvs set up specifically how you want them though.

there should be maxscripts that can do that already out, look at www.scriptspot.com