The commentary track on the TPM DVD is pretty bad from what I have seen. Just a lot of "this was done with CGI, that was done with CGI." McCallum appears to have made the movie, because George seems to be squarely in the background. I enjoy commentary tracks that are a little more anecdotal- the one from Ghostbusters comes to mind.
I liked the documentaries, but some ominous things were said by GL. He likes Lloyd because he's "unpredictable," he recycles plotlines because they are supposed to "ryhme" like a tonal poem (puh-lease), and "you can screw these things up, I made American Graffitti 2 and it made about 10 cents."