As for specific Opeth songs, here's some suggestions:
"Ghost of Perdition"
"The Lotus Eater"
"Face of Melinda"
"Windowpane"
"Bleak"
Not sure if you're into metal, but I feel like many people can at least appreciate their musical talent. The vocalist does both the growl and singing (extremely good at both), plays guitar, and writes all the music. Their songs are all long (like 10 minutes), and it can take a few listens through to "get" it. But, once you do, it's incredible. Also, they're progressive, so they're not strictly metal. They mix tons of genres. Their "Damnation" album is a 100% soft album.