Best solo piano recording...redbook CDs only...Jazz, easy listening, piano bar

Check out Rachel Grimes' "Book of Leaves".  Might work for you.  Not strictly solo piano but her album "The Clearing" is also worth auditioning.

Richter J.S.Bach The Well-Tempered Clavier released in 1992 RCA Germany. Not bar-type music, but serves the soothing purpose as none in the world near with full sounding piano able to fill up the room. It's an extraordinary ability of Richter to make piano sound BIG.

1: Keith Jarrett: Koln Concert - best selling solo jazz piano album in history
2: Liz Story: Solid Colors - wonderful late night music; beautiful harmonies and progressions
3. Bill Evans: Alone - hey, it's Bill Evans; 'nuff said

A couple of mental late-arrivers:

"John Cage: In a Landscape" performed by Stephen Drury.  Not the aleatory John Cage one might expect. 

If not already familiar with him, might be a good time to make the acquaintance of Harold Budd.  His 2000 recording, "The Room" seems like it could be another that fits your requirements.

BTW - no claim is made that anything I've suggested is a "best".