I recently read the first hardcover collection of All-Star Superman and have to admit that it is probably some of the best Superman stories I have ever read in my life. I also have to admit that looking at the cover, which is a repro of the first issue's cover (which I own and have looked at many times), I never noticed that Supes was sitting on a cloud looking down over Metropolis. For some crazy reason, I thought he was sitting on a mountain somewhere, relaxing for a spell in-between crime-busting and galaxy saving activities. I've always loved the cover by Frank Quitely, but have to say I'm just a bit embarrassed that I never caught that before.
It's possible that I was thinking of this old Superman cover by Dan Jurgens. I mean, it's Supes on a mountain with snow. I can't think of any other valid explanation for it.
That being said, I can't wait for HC collection #2. For whatever reason I stopped buying these after the first issue and it's nice to be able to get a chance to read these for the first time.