some suggestions: _

Sheri S Tepper
Grass. Raising the Stones, A plague of Angels. many more, This is Powerful writing indeed, dealing with big issues, very nicely wrapped
in adventure stories. i tend to race through her books the first time to FIND OUT WHAT HAPPENS. Then (amazingly) pick them up again about a month later to re-read more slowly and discover a lot more meaning to them.

Lois McMaster Bujold
One set of books is written around a "boy soldier" - don't be mislead by the cover blurbs - she is writing about people facing harsh challenges, but with a nice touch of humour.
Her more recent work is quite different set in an "other" world it MAY be classed as fantasy - mediavleal fiction -
starting with The Curse of Chalion, then Palladin of Souls, - i have heard rumours of a third book in this set - not available in Australia yet, again dealing with characters facing huge challenges.

Octavia Butler.
Stunning work. She uses SF to examine questions like "what is a human?" - but with a clear and personal voice. - look at the earthseed tribe here for more about her. Her Earth seed books are - um, possible near future based, very well written

Thanks!! I am going back to re-read the LeGuins, now. Starting with Always Coming Home.