I've always been a big fan of listening to multitracks of hit songs as a learning experience. It's so much fun to hear just how perfect or imperfect the tracks are. Until recently, these multitracks were pretty difficult to find unless you already knew the band or artist, or their producer or engineer, and they were kind enough to let you play with them.
But everything has changed now with YouTube, where you can find a wide variety of dissected material. It's been suggested that a lot of this comes from a guy who works for the vault company that houses many of these master multitrack tapes for the major labels, but who really knows (I'm sure the label's business affairs sure would like to know)? The fact of the matter is that so many songs are now available for our dissected listening pleasure, and any student of record production should take advantage of them.
Here's a great example of one of the most sophisticated hit songs ever made - Queen's Bohemian Rhapsody. This video gives you a look at all 44 tracks to provide a great idea of how the song (especially the vocals) is layered.
Listen to how in-tune all the vocals are (a tribute to Freddie and the band) and how tight everything is in the days way before Beat Detective and digital editing. Sure there are a couple of things that a sharp ear will detect, but you'd probably leave those in today anyway because the feel is so good.
The only thing better than listening to this video is having the tracks to play with yourself, but you'll have to find that on your own.