Anything by Tad Williams. The guy's a great writer.

Harry Turtledove's World at War series....(basically WWII in a fantasy world.

Susan Coopers Dark is Rising Sequence.

Morgan Llewellyn

I loved Marion Zimmer Bradley's Mists of Avalon...but since it came to light the horrible abuse she perpetrated, or at the very least enabled, really leaves a sour stain on my stomach. I can't read it anymore.