Some of the best authors wind up with movies made of their works that are really horrible. Tom Clancy, Steven King, and Michael Crichton come to mind.
While Speilberg is a master story teller, and Jurasic Park was a wonderful movie, it's nowhere near as good as the book. I was on a long flight, and had a chance to start reading Congo, but I had already seen the movie. Again, no contest there. The book was so much better. In fact, I seem to recall seeing an article about a new species of ape being found in Africa.
As a movie, I think Sphere really sucked, but the book was pretty good.
The exception to the rule is with "The Thirteenth Warrior." It was based on Crichton's "Eaters of the Dead." The story was pretty good, but I really loved the movie.
Mark
I'd add Snow Falling on Cedars to your list - the book is extraordinary.
Regards.