Chris Claremont is my prototype for what a good comic book writer does. While Stan Lee may have invented the X-Men, remember that it was Claremont that made packed it with all the important characters and metaphors it has today. The reason Bryan Singer was able to do those really amazing first two films was because of the groundwork that Claremont, not Lee, laid.
One thing that has always puzzled me is why, after an amazing run on various X-books (but mostly on Uncanny X-Men) from 1975-1991, he quit. Here, in footage from the Motor City comic con 2008 (in Novi), he answers that question (at least for the first time I've seen--he's probably done it lots of times other places), as well as some others about the film franchise, etc.