I don't read a lot of fantasy novels, but I second the vote for anything R.A. Salvatore... excellent novels all of them especially the Artemis/Jarlaxle series (3 books).
But I most often read espionage/spy/secret agent type books by the following authors in no particular order:
David Baldacci. He mostly writes stand alone novels, but have a few double, triple and quadruple series'. The series about the Camel Club is excellent.
Robert Ludlum is excellent as well. The Jason Bourne series is way better than the movies... and much different as well.
Nelson DeMille is a great writer. I love his characters (very detailed).
Robert Crais' Elvis Cole stories are extremely funny. I don't think I have laughed out loud at books as much as I have reading his novels.
Joseph Finder is a master at weaving intricate plots without losing the reader. You see it unfold slowly just as the characters do. Great stuff.
And then the classics that I would recommend highly:
George Orwell's - Animal Farm, 1984, and Of Mice and Men
JD Salinger - Catcher in the Rye
JRR Tolkein (of course) - Hobbit and LOTR
James Bradley - Flags of our Fathers
There are tons more but my old brain can't think right now.