In no particular order, I like:
"Moonlight Seranade" LP, Laurindo Almeida/Ray Brown. Almeida plays Beethoven's "Moonlight Sonata" on the guitar while Ray Brown weaves "Around Midnight" in and out on the bowed bass. (Detail, dynamics, low frequency articulation and information)
"Yulunga" Dead Can Dance CD (Percussion, vocals, image placement)
"Savitri" Gustav Holst/Purcell Singers LP (Remarkable LP on the Argo lable. Great test of the ability of your system to reproduce the female voice of Janet Baker, as well as soundstage. The male voice starts way in the rear and moves forward and to the right, then across the front of the soundstage as the piece progresses)
"Hebrides Overture (Fingal's Cave)" Mendelssohn. Maag/LSO 45rpm Speakers Corner reissue of the original Decca LP(Full orchestral work with a wide, deep soundstage)
"Firebird" Stravinsky. Leinsdorf/Los Angeles LP from Sheffield. (Enormous dynamic swings, subtle inner details, large loud percussive sections.) Performance is not quite a forward and well executed as the famous Dorati/London mercury release, but still a mighty fine test of a systems overall dynamic capabilities.