Jack McDevitt - Engines of God - Sci Fi, but not really, just in the future. Sorta like a mystery. Very intelligent.
L.E. Modesitt - Recluse Series (first book is The Magic of Recluse) - Fantasy, but original, not standard. Very interesting idea of good and evil/ chaos and order
Robert Jordan - Wheel of Time series (First book is The Eye of the World) - Fantasy, but again, original, not standard. Great storyteller. Even my mother liked these.
R.A. Salvatore - The Dark Elf series (First book is Homeland) - Fantasy. This is standard cookie cutter fantasy but I love Drizzt. These aren't going to make you think much, but they are fun to read.
Stephen R. Donaldson - The Chronicles of Thomas Covenant the Unbeliever (First book is Lord Foul's Bane). - Fantasy - Another great original fantasy series. The hero is so angry and pathetic.
Michael Creighton - Eaters of the Dead - (became the movie The 13th Warrior but you know how books are always better than their associated movies.
Ok, how's that for a start?