The first Quarterfinal bout,
Flowers for Algernon defeated the last Heinlein novel in the poll,
Stranger in a Strange Land. So one old master down, but we still have works by Asimov, Herbert, and Clarke in play.
This week though, two relative upstarts. Hitchhiker's Guide was published in 1979, and Ender's was published in 1985.
However, neither novel was actually the stories original form. Ender's Game started out as a short story/novelette, in Analog Magazine, 1977. I've never read that, but I suspect it may in some ways be superior to the long form novel.
Hitchhiker's started life as a radio drama from the BBC, in 1978. The first series was six half hour episodes, and the novel was adapted from just the first four. A second radio series from 1980 had another six episodes. The novel
The Restaurant at the End of the Universe adapted material from all 8 episodes not covered in the first book, but it covered them very very loosely. There is lots of material in the radio series that has never made it onto the printed page, and some of it is fantastic stuff. The ever-evolving Haggunenons and their hatred of rotten-filthy-stinking-samelings. The Shoe Event Horizon. The final scene in which Arthur and his girlfriend Lintilla steal the Heart of Gold, leaving Zaphod and Ford stranded with the man who rules the universe.
If you're a fan of tHhGttG and haven't heard the
Original Radio Series you owe yourself a listen.
edit: links EP-ized.