For classical (and a few other things), there's a "Recordings in the Round" appendix to each of my "Music in the Round" columns. Access them at: [url]www.stereophile.com/musicintheround[/url]
For popular music I would recommend, (1) Beck-Sea Change, a great album that is really well recorded and has a fantastic multi-channel mix,(2) Cowboy Junkies-Whites Off Earth Now, this is the Junkies debut album. Not nearly as well known as their sophomore record-The Trinity Sessions, and that's a pity because I think it is a superior record. This is a MFSL limited edition numbered release, and is quite possibly the best sounding multi-channel SACD I have ever heard in the popular music genre.(3)The obligatory choice, Pink Floyd- The Dark Side of The Moon, A stellar re-mastering and re-mixing job on one of the most loved records of all time. No SACD collection is complete without it.
As far as jazz goes, it's hard to go wrong with just about any of the multi-channel releases from Telarc, Chesky,Concorde, or Groove Note. Also Headhunters from Herbie Hancock is very well done if a little heavy handed with the surround effects. The obligatory disc for jazz is of course Kind of Blue from Miles Davis. This is an excellent re-mastering job. It's hard to tell that this version is 5.1 until you switch to the two channel layer and the soundstage collapses.
I can offer many more recommendations but this is a good start, hope it helps.
P.S. One multi-channel SACD that receives a lot of good press but that I feel is overrated is Dire Straits-Brothers In Arms.
OK, here you go. Trust me on these:
(all multi-channel surround sound)
Fourplay - Energy
Spyro Gyra - Wrapped in a Dream (dynamite)
Toto - Toto IV (Roseanna, Africa, etc)
Elton John - Honky Chateau (fabulous sound)
Carole King - Tapestry (a classic)
Bob Dylan - Blood on the Tracks
Tchaikovsky 1812 Overture by the Cincinnati Pops Orchestra