Kate Wolf's Give Yourself to Love

but perhaps you could have instruments...
just no amplification...perhaps ones
with some volume...such as bagpipes,
nyckelharp, or some resonator type

this would carry better than a voice..
will you plan to have multiple singers?

a pretty waltz is Give Me Your Hand
(i do not know of lyrics for this--i am thinking instrumental here)
or as mentioned above, Mairi's Wedding