Without derailing this thread too far off topic, there's obvious ones like Dark Side Of The Moon and Aja as mentioned above. I'm sure there has to be a thread or two with music as a subject here somewhere. I know there's an excellent one for live concert discussions.
I find not all music lends itself well to multi-channel SACD, and it's fairly dependent on how the engineer mixes it. What would he do with something like the Police where it's a three piece band for instance? In theory you could easily over-gimmick it.
But something with multiple layers of instruments and ambiance like DSOTM obviously lends itself well to that medium. Also a lot of SACD's have both 5.1 & 2.0 layers, and the 2 channel layer is also higher resolution than CD's.