Hey, one bit of advice--older recordings and sonic beauty are not mutually exclusive. In fact, it's often quite the opposite.
Recordings made the old fashioned way (no overdubs, no compression/limiting, no complex ADC conversions, no processing, no equalization, etc.) with musicians all playing together with minimal mic use has yielded some of the most spectacular recordings of all time.
Some of these old master tapes have been lovingly preserved and then re-cut to digital using the best mastering gear and minds available (not early digital), has made for excellent re-releases.
Likewise, there's a lot of new music that's not lovingly produced. I'd respectfully suggest you re-examine the original assumption and seek some other views as well.
As for selections (and I know this just sounds so damn predictable), but I was just listening to "Kind of Blue" this afternoon, and for me, each new listen is better than the last. Keep in mind that while Miles Davis, John Coltrane, Charles Mingus, and many others may not be solely balladeers, their ballads are simply magnificent.
Bill Evans (as noted earlier) is a great suggestion. Look for some Art Pepper as well.
If you want to find some really "minimalist" music, look for "Lords Tundra" by Dean Peer (bassist) or "Wood" by Brian Bromberg (bass also).
I don't really have much in terms of Spanish Guitar, but there's a jazz guitarist named Grant Geissman that's very melodic.
Finally, a favorite of mine is Ry Cooder (guitarist) with V.M. Bhatt on "A Meeting by the River". It's an improvisation with a definite East Indian feel, but is very melodic and amazingly recorded live.
