Since my visit to a Star Trek Convention in the mid 90's where Steve Arnold and other Star Trek brass (ok, its getting late... misspelling easily) nearly caused a riot at a Creations Convention in NYC by stating that Star Trek was not Science Fiction but Science Fantasy, I really dislike the term science fantasy. Fantasy is just that fantasy. Science Fiction is the authors interpolation of science today and conjecturing what it may be tomorrow. Fantasy is something we know will never be in tomorrow. So Dune and so many others are Fantasy, not science fantasy. I am a stickler on that because there is no real science to base fantasy on.
Don't get me wrong, as far as fantasy goes, Lord of the Rings and Dune are phenomenally great fantasies.
PS Creation conventions were NOT the first Star Trek Conventions. Joan Winston and her friends put on the first Star Trek Convention, and there is even a debate if there was one before that one in 1972. I know, my friends and I were encouraging Creations to run Star Trek Convention back in the mid to late 70's and they said, it was not there cup of tea. They were only interesting in Comic Conventions. This was at their Long Island Store where they started. Creations was the first Trade Marked ST Convention which put most if not all the fan run conventions out of business.