Great Recordings, Sonically Speaking - and Why.

I think many of us would accept that artists such as Pink Floyd, Steely Dan, and Dire Straits have consistently put out music that was at least originally recorded to a high technical standard. [I'm not too sure what the loudness wars may have done to subsequent reissues, but even so, the tone and timbre thankfully tends to remain intact.]

However there must be plenty of lesser known recordings out there that could be said to be of a high sonic standard.

One such recording that I like to put on in the background whilst I'm doing other things is a piano recording that features wonderfully lush timbre and some delightful tunes.

This one is The Disney Piano Collection by Hirohashi Makiko and to me it makes a lot of other piano recordings sound a little washed out.
Jazz, by Ry Cooder is an excellent and interesting LP.  I see Mobile Fidelity Sound Lab is referenced above.  I purchased their very expensive  re release  of Ry Cooder's Paradise & Lunch.  Sad to say it was money wasted as my original copy of the same LP sounds every bit as good.  I guess taking good care of your vinyl over the decades really does pay off.  
Another few sleepers: a first gen pressing of: Randy Newman’s Sail Away; Roberta Flack’s Chapter Two, 10cc’s Deceptive Bends; David Crosby’s If Only I Could Remember my Name; and Brubeck’s Countdown — Time in Outer Space. 
Robert Gordon/Link Wray (the one with the black-and-white cover, not the pink one).  Awesome recording.
@tostadosunidos: Yes! That album sounds almost like a direct-to-disc, so alive and immediate. Produced by Richard Gottehrer, who didn’t make Blondie sound nearly as good.

Gordon did the first version I ever heard of "My Gal Is Red Hot", a killer Rockabilly song originally by Billy Lee Riley. I didn’t yet know it, but Ronnie Hawkins recorded the song in 1959, before his band The Hawks included future members of THE Band.

Gordon had a number of superb guitarists after Link Wray, including Chris Spedding and Danny Gatton. I saw Link live on his last trip through Los Angeles. He needed help getting onto the stage, but could still play great!
I often go by labels.
50’s and 60’s RCA records, especially Chet Atkins, sound great.
60’s and 70’s Electra Records sounds pretty good, too.
And Rounder Records stuff sounds excellent as well.
I would also add that legacy artists like Dylan, Young, Petty, and Mellencamp care a lot about sound quality, and virtually everything they put out has great sound; I wish the same could be said of Springsteen.