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

bliss,

You write that "Classical examples are also very welcomed." Here’s my favorite (of rather many; I listen to mostly "classical"): Beethoven’s complete incidental music to "The Creatures of Prometheus," performed by the Orpheus Chamber Orchestra (DGG 447 911-2). The overture is well known, but the complete music is not. Great "middle period" Beethoven, though.

Track 7 is especially compelling. It begins with a harp on the left in the rear, which is joined by a flute—also on the left, but in front of the harp; then an oboe on the right, which is answered by a clarinet just to the left of the oboe (so, about in the middle of the orchestra). Then, a solo cello comes in on the far right, to the oboe’s left but in front of it. The stability and precise location of all these solo instruments is maintained throughout this movement, even when the orchestra is playing tutti. The realism is really something, as instrumental timbres are very accurately represented as well. And the recording (all digital) dates from 1987! Not SACD, not 20-bit. Shows how important the abilities of the recording engineers is.

My current picks are any of the Boston Symphony  recordings of Shostakovich symphonies by Andris Nelsons. Number 4 is my favorite. Stunning recording quality. You can hear the room. And they are great imaging tests because Shostakovich liked to send melodic motifs back and forth across the orchestra, often pairing two instruments at a time. Good both for lateral imaging and back-to-front. 

Dominique Fils-Aime / Stay Tuned does a fantastic job of projecting depth and width. An added bonus is that her music is extremely yummy.

Female voice: Madonna singing Vogue. Sound comes from behind and left of seating position and goes to right and behind right speaker at the beginning. At the end, "Vogue" repeats 4 times, in front of you, closer, to the left and right of you, then behind.

Deep Forest Walk in the Desert plays with phase to be center stage, in front of the speakers, then beside and behind alternately. Seems to remain independent of speakers altogether, and that was only an mp3 version.

For me sound stage depth encompasses a larger area than my listening space.

"What now my love"   A hipped up, jazzy cover by The Peddlers, Tidal/Masters.