[Nono]

Like you I'm a great admirer of Scott as well, so I'll leave the more
technical solution to him.
But I'm wondering:
Do you know how you want the songs to sound or how the songs should
sound before you start recording?
In that case you'd choose the (microphone) technique to achieve that
sound, otherwise you could accept the recording sounding like it does
and apply the (mixing) technique that best suits that particular
sound.
The same applies to the quality (I don't mean this in the wrong way)
or the style of playing of the musicians; they too have to accept that
the way they sound is the way they sound.
Secondly; do the musicians leave you the room to do your job? While
they know how to play their stuff and may have their ideas about how
they want to sound, what you should obviously respect, they should
also know that you are the one who knows what the possibilities are
and what is needed in order to achieve it.

The reason for me saying this are your remarks:
" it is very hard to communicate to the player that they might need to
play differently in the studio than in a hall" and ".....often, medium
rooms sound pretty realistic to the sound, but the players both like
large hall reverbs like on most other CDs like theirs." and "....that
helps some, but both players like it better with wide harp and flute
in middle."

I had an experience with a female singer that wanted her recording to
sound like her favourite singer, while she did not sing at all like
like that. Because of this she refused all my attempts to make the
recordings sound good in her own particular style. It was like trying
to get a trombone to sound like an alto saxophone.

Good luck.