We're a total audiobook family--dh edits them for a living, I proof all his work, so I listen to them daily, and the kids go to sleep to them every night, and listen in the car sometimes as well. I second the Beverly Cleary books. Stockard Channing's narration is wonderful. She does the best kid voices ever. Neal Patrick Harris also did some of the Henry Huggins books, and is also excellent. Our kids also love Charlie and the Chocolate Factory, read by Eric Idle, Charlie and the Great Glass Elevator, also Idle, and James and the Giant Peach, read by Jeremy Irons. There is also a brand audiobook of Alice and Wonderland out, read by Michael York, that is excellent.
Random House has a series of stories read by celebrities, all with original music, called Rabbit Ears, that are very, very well performed and produced--folk and fairy tales, stories from around the world, tall tales and legends, etc.
Also, Jim Weiss and Bobby Norfolk are wonderful storytellers, with many audio productions available.
We get all of these out of the library on CD, by the way.