Well recorded solo piano and solo acoustic guitar?

Simply Eva

Michael Hedges-Aerial Boundaries is excellent.

Chuck Leavell- Forever Blue

Solo piano:
Liz Story, any of her albums but I really like "Solid Colors" for setting a mood and staying there.
Also Carol Commune's "Intracoastal" is one of my favorites. Ran into her at a music store in Jupiter Florida a number of years back and found out that she was a wonderful solo pianist as well as a delightful person.
Newer is "The Chopin Project" by Ólafur Arnalds and Alice Sara Ott. This is available on LP, well worth the extra $$ over the CD, and is a wonderfully compelling performance and recording.
Solo Guitar:
Ted Greene "Solo Guitar", well recorded album and really really really stellar performance that stays in the same mood throughout.
Michael Gulezian "Language Of The Flame" is a masterpiece as well.
Enjoy!

Thanks, all, for the recommendations. I'm chasing them down one-by-one.

Slaw3: Which store in Jupiter? We're heading down there in a couple of weeks.

Egberto Gismonti..both solo piano and solo guitar. Great recordings.

Also, W.A. Mathieu - Available Light (solo piano)

Michael Hedges Solos--guitar 17/18 cuts. Up your alley.

Bruce Cockburn-speechless, for guitar

I agree with Slaw3! Liz Story-Solid Colors. Might not be the best solo piano recording out there but the sound/performance aspect is tough to beat. Her composition Peace Piece(tribute to Bill Evans)is flawless!

CARLOS BARBOSA-LIMA " PLAYS THE MUSIC OF
ANTONIO CARLOS JOBIM& GEORGE GERSHWIN" on
Concord Records is one of the best solo acoustic guitar records
that I own. BTW, you can find many of his albums on Ebay at
reasonable prices !

Bach on a Steinway CD. Very well recorded piano.
Peder Riis classical guitar CD on Opus3 recordings.

Here are two of my favorites. Fantastic sound and performances:

http://www.ebay.com/itm/JOHN-WILLIAMS-AND-JULIAN-BREAM-Live-DBL-LP-Classical-Guitar-RCA-Red-Seal-79-/291176929775?pt=LH_DefaultDomain_3&hash=item43cb7f59ef

http://www.ebay.com/itm/JOHN-WILLIAMS-Greatest-Hits-The-Guitar-LP-Vinyl-Record-M-31407-Columbia-1972-/191609819579?pt=LH_DefaultDomain_0&hash=item2c9cd5d1bb

Oregonpapa, I'm afraid John Williams is a bit frisky for the OP. He knows how to crank up the tempo.

Solo guitar -

Julian Bream for classical. He is a classic.

Terra Guitarra has 2 new Spanish influenced CDs, Dragonfly and Firelight. They are a duo, but if you like Spanish style, I think you will like them. “Dragonfly” debuted at #4 on the ZMR World Music Radio Charts and was Nominated ZMR Best Instrumental Acoustic Album of the Year.

Check out any of George Winston's albums on the Windham Hill label.

Clive Carroll, Tommy Emmanuel

Tommy E. is definitely not low-keyed. Totally opposite.

Ed Gerhard, Sunnyland, Any CD from him.
Bill Evans, Alone, Alone Again
Joe Pass, Virtuoso 1-4, Songs for Ellen, Unforgettable
Pink Guitar, Songs from Henry Mancini done on solo guitar.
Laurence Juber, Best
Joe Diorio, Italy
Gene Bertincini, Jobim
Earl Klugh, solo,

+1 for Pink Guitar--every track is a different performer, each one great.