The Left Hand of Darkness- Ursula K LeGuin. Incredible feminist scifi, truly ahead of its time.

Sunset Song- Lewis Grassic Gibbon. One you might not know at all. It's the story of a farm girl during WW1, written in a synthetic version of the Scots language. It's not hard to read at all though. A story of perseverance during difficult times, and our connections with the land. Chris Guthrie is one of literatures best heroines, up there with Lizzie Bennet and Jane Eyre!

Casino Royale by Ian Fleming, or Greenmantle by John Buchan. Or Our Man In Havana by Grahame Greene. I didn't see any spy fiction on your list!