Tim, you really did your research on this one. I agree with your list. Herbert is right where is should be. Using your baseball phrase, he had that one memorable season that will be forever remembered but his body of work without Dune...we wouldn't know who he is today. Just a side note someone PLEASE tell Brian Herbert to stop butchering his Dad's novels!
Only one I would have added would have been H.G. Wells but if you are doing this after the 1920's I can't argue with your list. It should just be pointed out that without Wells we don't get a lot of those writers today.






I was wondering if Turtledove was going to appear, but I tend to agree with you in excluding him; alternate history is really a different genre than science fiction, even if it has science fiction elements to it. The Guns of the South has time travel as the premise for what happens, but I wouldn't consider it science-fiction. In fact, I don't even know if you could call the Worldwar series and its sequels pure science fiction.