Best recordings to demonstrate soundstage?

I am interested in imaging and soundstage. I have picked up a pair of Thiel 3.6's and would like to test their imaging potential.

Box speakers are something of a problem for me because for some years I have listened to large planars, which throw up a huge soundstage. The Thiels have a much more constrained soundstage as compared to planars, yet they can seem wide and accurate and at times. With the right recordings they are absolutely amazing.

Hooverphonic and Morcheeba are 2 bands that I tend to use. Within their music there is so much going on. Sounds flying left and right, beautiful vocals centered, with layered vocals surrounding.

Can you help me increase my list? I love all kinds of music period. In your experience what is the best music and or tracks for highlighting soundstage?

Thank you,

very good soundstage and overall sound quality is Dick Hyman,From the Age of Swing-Reference Recordings.Also Ray Brown,Live at Sculler's,Telarc, and Ray Brown,Live at the Loa-Summer Wind-Concord Jazz.3 of the better ones IMhO.
I second the recommendation for "Sky Blue Sky" by Wilco (just wonderful, crisp production.) In that vein, I would also heartily recommend "Sea Change" by Beck. Its the one album I reach for again and again when I want to demonstrate the strengths of my system.

Also, if you can find it "Pleiades" by Xenakis on BIS (cd-482). Wonderful sense of place and spaciousness.
Go ahead, make fun of me. The Veggie Tales worship songs CD seems to have been recorded with only one microphone, and you can hear every person in the room in their own space. Even if you don't like the music or the message, its use as a diagnostic tool makes it a totally worthwhile purchase.

The first track, befor the music even starts, features a couple of adults holding a conversation and kids scattered throughout the studio. A good system will put the voices all over your room, just like they were in the studio.
Hi, I'm 8 years late to the game, but hell I might as well contribute here than start a new thread.

The Punch Brothers' album "Antifogmatic" basically changed my concept of what great imaging should look like. Side 1 actually sounds like it was concepted as an audiophile demo. Chris Thile is a virtuoso prodigy, and is deeply involved with his recordings, even producing on some. His deep involvement with the mastering of his music is vividly on display in this album.

For a stripped-down practice in soundstage, The Staves track "Icarus" places 3 female voices in precise locations between the speakers with consistency.