My favourite Wyndham novel is The Crysalids. Haven't read Trouble with Lichen. The triffids terrified me on telly as a child, I think I read the book later but don't recall much about it. A good writer.
I've read a few of those Sci Fi Masterworks. The Lathe of Heaven is superb and reminded me how much I loved the Earthsea series by the same author. Probably the first fantasy series I read and it stands up well to any other. 'I am Legend' by Richard Matheson is also superb. I'll probably start picking off that list as well, perhaps we could do a book swap?
Poul Anderson was someone I first came across via short stories. Science fiction seems to lend itself to this format. I prefer Philip K Dick's short stories to his novels, he's not great at character but his ideas are, er, out of this world...
Dune is mentioned above. The first novel is one of the greatest acts of imagination ever committed to a page. The depth of the world he creates is mind blowing. I stayed with the series but eventually I felt it lost its way. The interesting thing about the first book however is that several people I know who have no time for the sci fi genre have read this book and loved it. As they should because it's a classic.
Talking of Dune reminded me of another series linked to the effect climate has on civilisation. Brian Aldiss is a British writer, he wrote three novels set on Helliconia, a world with something like a 1000 year cycle of seasons. An excellent read.
I've recently bought two collections from the Fantasy Masterworks series, Jack Vance's 'Tales of the Dying Earth' and a collection of the short stories of Lord Dunsany. Jack Vance is just a brilliant writer, regardless of which genre or box you care to put him in. Lord Dunsany is often cited as the father of the genre. If you want a flavour of his writing try
this little gem. It subverts the traditional telling and has one of the best endings of any short story.