do the trees have a hand in giving it 'the feel'? Or are you talking purely about the arrangement and proportions of the stones themselves?....

No, I agree strongly, "the natural" is the other major contributor. God this makes me feel old in TMA terms as it was about 2003 I put this forward here! We are attuned to trees not pavements, moss not concrete, thatch not tile etc. Put a bit of ivy and lichen on rocks and avoid straight lines and everything, including monuments, looks and feels better....