I love
Ruth too, both as a fn and mn. I don't consider two syllables excessively long! And if you take
Ruth as the opposite of ruthless, then there's a thematic link with virtue names like
Patience that hardly shows but is still pleasing.
A friend's daughter uses her full name -
Ruth Mary - for professional purposes. I don't like the rhythm much, but a double name like
Ruth Marie or
Ruth Elaine might be nice and could be used on occasion.