Your Go to CD to Impress

+1 to wgutz for the Lindsey Sterling mention. She's awesome! Here are mine....

Andreas Vollenweider - Book of Roses, first three tracks
Dire Straits - Private Investigations
Neil Young - A Man Needs a Maid, Live at Massey Hall
Diana Krall - A Case of You, Live in Paris
Dave Brubeck - Take Five (of course)
David Gray - Please Forgive Me, White Ladder
Patricia Barber - Anything from Cafe Blue or Live in Paris

In keeping with the spirit of the OP's question, I'm eliminating all SACDs (such as Norah Jones' "Come Away With Me"), DVD-As and other specialized discs (except XRCD which is a standard CD). One of many possible great demo CDs is: "Mapleshade's Music Festival". Some have mentioned Patricia Barber but the exaggerated echo applied to her voice eliminates these otherwise excellent recordings, IMHO.

@andy8400 yours is an excellent tip! I wonder why Mapleshade CDs are usually disregarded as audiophile delights, they are dirt cheap and sound better than most XRCDs, RR, or CDs from Naim or Linn labels. No blockbusters in Mapleshade catalog, but the sound is stunning! An excellent demo/advertisement for their hardware though!!

Depends on the person: for a Baptist minister friend I played the Messiah; 
for a young guy who wanted soothing strings, a Mozart string quartet; 
for someone who liked it lively, Armik, the neo-flamenco guitarist;
for classical nuts like me, either the Bach B minor mass; or to check out the bass, Rachmaninoff Symphonic Dances...
Any random person? James Taylor. 

Try to find a CD or record they love or already are familiar with.  Then blow them away with how it sounds on your system!