This thread and the current "Future Peek" thread raise a good point (tangentially) about the difference between a good song and a good jam vehicle.
For example: To me, Rufus is just a good song, but a great jam vehicle. The jam is tacked on to the end of the composed portion and could conceivably come in the middle of Great Big Fiery Ball or Beef Barley or anything else, and Rufus gets more credit than it is due as a song because of this. Metropolis, on the other hand, is very well composed AND is a great jumping off point for jamming.
Of course, the specific examples are all based on opinion, but I hope that at least clears up what I\'m trying to say about the difference between a good song and good jam vehicle.