If you haven't tried them, you need to...

It's only one person's opinion, but if your CD player has the capability to decode HDCDs and you're not taking advantage of it by buying HDCDs, then shame on you. HDCDs add a level of detail that red book CDs just don't have. And don't overlook CDs with SBM (Sony Bit Mapping); you can find them hiding in the store racks if you look. Also, JVCXRCDs are out of this world, taking the detail to a whole new level. They cost more, but I think they're well worth it. I have the Eagles' Hell Freezes Over, and it's great. If I come across any of my favorite groups in any of the above formats, I buy it, even if I already have it in my library. They're that much better. Don't know what trips your trigger, but I recommend you give a listen if you're not familiar with these formats.

If anyone has stumbled across something else out there that I should listen to, please let me know.
Launche - Acousticsounds.com and Musicdirect.com both sell HDCDs as well as other formats.

Alpass - I live in the past, so forgive my taste. Here's some of my favorites:
Creedence Clearwater Revival - 20bit
Billy Joel/52nd St - Sony Bit Mapping (SBM)
Pink Floyd/Wish You were Here - SBM
Boston - SBM
Santana - SBM
Simon & Garfunkel/Bridge over Troubled Water - SBM
Sly & the Family Stone/Stand - SBM
Birds/Greatest Hits - SBM
Bad Company - HDCD
Crosby, Stills & Nash - HDCD
Alan Parsons Project/Works - SBM
The Cars - HDCD
Buffalo Springfield/Again - HDCD
BeeGees/Greatest Hits - HDCD
The Band/Greatest Hits - 24bit
Eric Clapton/Reptile - HDCD
Chet Atkins/Master and His Music - HDCD
Beach Boys/Pet Sounds - HDCD
Van Halen - HDCD
Dire Straits/Best of - HDCD
Plus various Reference Recordings in HDCD - Dick Hyman, Pomp & Pipes, Turtle Creek Chorale - Postcards, etc.

Like Marakanetz, I buy ony the artists that I like. But like I said in my original post, I'm a sucker for a better format if I come across the same album. Unfortunately, I never took the SACD or DVDA plunge. Still not sure if one or both ever really caught on. So I'm clueless as to what they offer and which is superior.

Check the archives by searching HDCD for plenty of recommendations. Also try this http://www6.head-fi.org/forums/showthread.php?t=67082&highlight= for a large list.
I'm a big fan of HDCD.
Here's the most comprehensive list of HDCD's that I know of, just click on the database button...

Others of possible interest:
Joni Mitchell cds--several titles
Roxy Music--several titles; Avalon is a must!
Brian Ferry--several titles; Boys and Girls is a must
The Cars-same title; a must
Buffalo Springfield--all 3 cds
Steve Stills-Manassas
Hey Rockyboy; great, varied, selection of music you listen to! How's that Sly Stone CD? I love his stuff! Also, the Buffalo Springfield? didn't know that was HDCD