What are your favorite songs or albums for illustrating a deep soundstage?

"If You Leave Me Now" (Remastered LP Version) from The Very Best of Chicago: Only the Beginning album. The album artwork has Chicago in green on a brown background. Great detail, separation between the instruments and soundstage. 

Dire Straits-Private Investigations 

Almost any song by Dominique Fils-Aime

Bella Sonas- Enamoured (album) every song on this album has great depth

Jethro Tull Thick as a Brick. It’s one of the best produced albums you can find.

Pink Floyd The Wall. From beginning to end the soundstage moves. Pink Floyd should be you go to for bass test. I still have not found better drum production.

@pharaoh - Madonna's Voque used a processing called "QSound" that, if I remember correctly, was relatively new back then in '89/'90.  It used (essentially) phase cancellation techniques to get that soundstage that you are hearing. 

I distinctly remember discussing this processing back in college at the time during my recording classes and I don't think it was all that popular of a processing technique since few listeners of modern pop would sit behind a decent stereo in the sweet spot to be able to really hear that processing.  I think there was only maybe a handful of albums that utilized this processing.  However, I agree, it's pretty cool.  Check out Rescue Me on Madonna's Immaculate Collection greatest hits compilation for the effect on the thunder in that track.

Listening to some Heart last night I was amazed by the sound stage of Dream of the Archer.  And it is readily available everywhere I imagine.