In 2 years Doctor Who will be 50. How many other TV shows have been around that long, exploring the same premise? They exhausted the standard time travel tropes about 45 years ago. The originality is amazing, and it manages to do it without flaming out like series like Dark Angel, Sarah Connor, etc, that just run out of ways of outdoing themselves. I confess it jumped the shark for me after Tom Baker, and I stopped watching, but the new series has been breathtaking and I would peg the best episodes of the whole run within it. The latest season has been less watchable though.

I don't really think Dark Angel flamed out, it just went in a direction that nobody cared about, and neither did I: all those animal-faced mutants.
But I really liked the first season, even if it was very derivative of William Gibson.
And sorry, I know this is getting off-topic.
Hey, what about that Heinlein fellow?