What are your top songs that you use to evaluate a new high end purchase ?

When I bring home a piece to evaluate ( I only evaluate at home, or another household ), I have a handful of  recordings ( songs actually ) I specifically listen to ( keeping in mind warm up time / break in time ) for the new piece, as I know, and enjoy, these selections ( on CD ). Rolling Stones : Under My Thumb > Sway > Wild Horses > Can't You Hear Me Knock'in ( Maybe another or 2 ). SRV : Tin Pan Alley. Led Zep : When the Levee Breaks > Stairway To Heaven. Sarah Vaughnn : All of Me. Sheffield Drum Record > The solos. Allman Brothers ( at the Fillmore East ) One Way Out. Blind Faith : Do what you like. I estimate this about 1 1/2 hour.  At this point, I usually know if I like it. If I do not like it, I would know much sooner. Enjoy ! MrD.
Here are a few well recorded performances that have to sing in captivating fashion, or I wouldn't want the system!  Each has its "tells" for revealing the sonic influence of a system change.

Shelly Manne & His Men - at the Blackhawk, Vol. 1 "Summertime"
Charles Mingus - Mingus Ah Um "Goodbye Porkpie Hat"
Grant Green - Idle Moments "Idle Moments"

Bach, Passacaglia and Fugue in C minor, BWV 582, Peter Hurford on organ
Bruckner Symph 7, Gunter Wand & NDR - "1st Movement" is telling
Debussy, Zoltan Kocsis on piano - "Images, Livre 1:  Reflets dans l'eau" 
Enrique Coria - Latin Touch "Verano Porteno"

Beck - Odelay "Where It's At"
Neil Young - Live at Massey Hall "Old Man"
Low Reed - Magic & Loss "Power and Glory"
Pink Floyd - The Wall "Hey You"

Interesting choices listed above.  Love the music selection but not many I would use for evaluating audio equipment.  I generally look for live recordings, and trio jazz music or music with sax, piano and stand up bass.  No electronic music or rock & roll as the recordings are usually compressed.  I use piano recordings so that I can evaluate the weight of the notes, the decay, and how much wood on the piano I can hear.  Sax I want to hear if I can hear the reed vibrating, and the tone, vocals hear the air coming out of the mouth and stand up bass the wood and definition.  Once I hear all that, then I cam confident that Stevie Ray and Duane and Dickey will also sound good.

Happy Listening. 
I agree with BigKidz that a variety of "live recordings (acoustic & electric) is essential, as is songs where the notes have a lot of decay (particularly acoustic piano). Big picture wise, have some male and female vocals, while also focusing on guitar, bass, drums and keyboards. Finding something with a string quartet or a full orchestra is also a good idea. Little picture wise, any song that gives you "goosebumps" is an automatic candidate; or, any song that you pick up subtle details on headphones but not your current speakers would also be good.

Some of my recent "live" favorites are: "Fools in Love/For Your Love" - JOE JACKSON; "No More Buffalo" - JAMES MCMURTRY & "First and Repair" - MONTE MONTGOMERY.

Some of my recent "studio" favorites are: "Get Inside" - JOHNNY A; "Try, Try, Try" - ALEJANDRO ESCOVEDO; "That is Why" - JELLYFISH or anything from "Turn Of The Cards" by RENAISSANCE. I also agree with Irish_Tim that "Babylon Sisters" by STEELY DAN is an excellent choice.

Good luck and happy speaker hunting!

I listen to alot of compressed studio recordings because of my musical tastes. Most all live recordings and higher quality audiophile recordings sound great. I need my system to sound good on everything. I know many people who only play audiophile recordings, and although I have many, I listen to it all. What I have realized, in every case, is that I am listening to recordings, and I am fine with that. As long as I am able to " get into the music ". Enjoy ! MrD.