I hope one, or more, of these suggestions will work for you:
Sci-Fi and Fantasy that are well written, interesting, and that I enjoyed:
"The End of Eternity" by Isaac Asimov
"Pastwatch: The Redemption of Christopher Columbus" by Orson Scott Card
"Dune" by Frank Herbert (first in a series, but fine as a stand alone)
"The Once and Future King" by T. H. White
"The Mists of Avalon" by Marion Zimmer Bradley (First in a series, also fine as a stand alone)
Novels:
"The Pillars of the Earth" by Ken Follett (I loved this book, set in the 12th century, a thriller with great story and characters).
"The Girl with the Dragon Tattoo" by Stieg Larsson , Reg Keeland (Translator) (1st in series)
Classics:
"Jane Eyre" by Charlotte Bronte
"Tess of the d'Urbervilles" by Thomas Hardy
"Great Expectations" by Charles Dickens
"Frankenstein" by Mary Shelley
"Don Quioxite" by Miquel de Cervantes Saavedra
"The Name of the Rose" by Umberto Eco
"Little Women" by Louisa May Alcott
"Moby Dick" by Herman Melville
"The Prince and the Pauper" by Mark Twain
"The Great Gatsby" or "This Side of Paradise" by F. Scott Fitzgerald