Best music Blu-rays I've heard:
Neil Young's Archives Vol.1 - stunning but pricey. £200 for 10 Blu-rays. Not just music, but it's all I go back to once I've viewed the film and photo footage.
I'm quite disappointed with the SQ of the recent Zep Blu-ray. I think the CD sounds as good/bad. Shame as they sound on fantastic form.
Other higher-rez formats I've enjoyed:
1) Neil Young's studio albums of the last decade. Most seemed to come with a DVD-A disc too. They sound great. Prairie Wind in 24/96 sounds fantastic.
2) Likewise all the remastered Talking Heads' CDs from a few years back also contained a DVD-A of the album. They sound great. Personal favourites are True Stories and Speaking In Tongues.
3) King Crimson's Crimson King re-issue contains a 24bit hi-rez disc too and that sounds excellent.
4) American Mavericks - Michael Tilson Thomas/SFSO. Modern orchestral music on SACD. Wonderful sound, dynamic and ever so slightly unhinged music.
5) Steely Dan's Gaucho on DTS-CD. I bought this by mistake a few years ago. It wouldn't play in my PS3 but my Denon UD had no problems.
Sounds fantastic, then again it would sound half-decent on a mangled TDK C60 tape too. It's a great recording, if you like your music in ultra-arid, knowingly etoliated form.