Orson Scott Card's Xenocide has been a bit of a disappointment, as his writing style doesn't quite fit the six hundred page novel format. However, one notable author penned far longer works smooth as silk. He was none other than the great James Oliver Rigney, Jr., a.k.a. Robert Jordan.
Never before had I read such a long book that never felt like it dragged. Robert Jordan could take ten pages of description and keep you focused no matter how dry it was at its core. In The Eye of the World, one piece of dialogue by Moiraine stretched out to about five pages. At the time I had never seen one character speak for so long (nor have I since, that I remember). It astounded me. Never once was my attention detracted. Brilliant.
There's much to say about Mr. Jordan. I have hardly begun to delve into his several million word contribution to literature and am yet to discover his secrets. I'll be sure to reflect if I ever find them.