What about C.S. Friedman? Her Coldfire Trilogy is one of the best out there. Not to mention the famous In Conquest Born.
Also, you might want to consider the Dragonlance saga. It was based on D&D, but developed to stand on its own. Yes, it is a little simple, especially when compared to the complexity of Robert Jordan and George R.R. Martin. However, the original Dragonlance novels by Margaret Weis and Tracy Hickman, while amateurish, have something lacking in more complex novels: content. Think about it; while Robert Jordan may write thousands of pages that span dozens of characters, little ever happens in his novels. They have gotten so complex that plot developement has slowed to almost a halt. The Dragonlance Chronicles is made of three books, each about three hundred pages long, and each are better than the combined whole of Robert Jordan's work.
The modern tendency seems to be towards thicker books, because readers assume that thicker=longer to read=better. It does not.
Sorry, went on a rant. Tad Williams is an excellent writer (I've re-read Memory, Sorrow and Thorn thrice), and I did enjoy the Wheel of Time and Song of Ice and Fire.
Also check out Orson Scott Card's Ender's Game (a classic), Robert H. Heinlein's The Moon is a Harsh Mistress, Melanie Rawn's Exiles, R.A. Salvatore's Drak Elf Trilogy (stop after the sixth book about the character, Salvatore does not know how to kill an idea) and finally everyone must read The Chronicles of Narnia (I will NEVER see that accursed movie, just ignore the religious stuff in it--you can only see them if you look). Oh yeah, the first Dinotopia is good for all ages.
Me: "I'm Bored."
Nearby Pedestrian: "Run for your lives! Every man for himself! Throw the elderly and weak (read: small children) to the ground as decoys, immediately."