You know, I just realized I never quite defined how I'm using the word "science fantasy". To me, a science fantasy is a novel set on a world that technically has sci-fi origins (ie, colonized by a ship from earth), but said people on the world have forgotten everything about that past, and usually have regressed to a mediaeval level of technology, so the story itself generally plays out more like a fantasy, with ancient complex machines sometimes taking place of ancient complex magic.
Anyway--blgarver...If you do ever read Pern, the order they were written in I think is the best way. Anne McCaffrey is an excellent writer for the first few books in any given series, but she has a tendancy to retcon things from old books (or maybe she just forgets they're there) to fit newer books. So a fact from one book can be contradicted by a fact in a new book, and if you read them out of order an older book can have some things that just don't make sense if you read a newer book first. Drives us fans crazy! So yeah, if you read newer books first, such as The MasterHarper of Pern, earlier books don't always make sense. So I reccomend reading them in this order...Dragonflight (used to have the green cover), Dragonquest (used to have the purple cover), The Harper Hall Trilogy (Dragonsong, Dragonsinger, Dragondrums), The White Dragon, The Renegades of Pern, Dragonsdawn, All the Weyrs of Pern. (Then there's some more books which are scattered around after All the Weyrs of Pern).