Layla is one of those songs that is complete unto itself - Like "Good Vibrations", it's essentially a modern mini-symphony.
The album's story is as full as an entire book - within a year of its recording, Duane Allman had been killed in a motorcycle accident, and Clapton had fallen into a heroin-fueled depression. Jim Gordon, (the drummer on the album who composed and played the piano coda)developed schizophrenia, and in 1983, was convicted of killing his mother, thinking she was a demon. He's currently serving a life sentence in a California prison, spending most of his time in the mental hospital.
There's a great film out there - You should watch the DVD Tom Dowd and the Language of Music
[/b] Tom Dowd was a recording engineer for some of the best music of the last half of the 20th century, and his story is very moving. For the movie, he re-mixes the original master tapes of "Layla", and gives a full history of the song and its creation. It's one of the best movies I've seen in years.
For a sneak peek, here's the trailer: Language of Music Trailer