I agree with the two post above, but arguably there is some well-known music out there that sounds great and would most likely impress even non-audiophiles. Here are a few suggestions from my collection:
Carole King "The Carnegie Hall Concert" on MoFi - incredibly well-recorded and a collection of her best-known songs; can't imagine it would not drop listeners' jaws hearing it on a high-end system for the first time.
Fleetwood Mac - virtually all of their records sound tremendous; if you have or can get a mint copy of "Rumours" or "Fleetwood Mac," I'd be surprised if they didn't appreciate how good they sound and are packed with hits.
Foreigner "Foreigner" sounds terrific; "Cold as Ice" and "The Damage is Done" have always put smiles on my non-audiophile friend's faces
Supertramp "Crime of the Century" has quite a few songs that should impress even those who are not big Supertramp fans. The entire record is superbly recorded.
Diana Krall - yes, I know, most audiophiles get nauseous at this point hearing her music, but for those who are not yet oversaturated, her records do sound great.
Pink Floyd "Comfortably Numb" from "The Wall." Amazing song that sounds equally amazing. Actually, the entire album sounds tremendous.
Sting "Fragile" from "Nothing Like the Sun." Sublime.