Soothing music...

Indie/pop stuff like A Fine Frenzy, Mount Eerie, Nini & Ben

Classical stuff like Chopin, Debussey

john williams, soundtracks

80's or 80's style electronic stuff like vangelis, kavinsky, tangerine dream

But right now i'd say Opera is my favorite. verdi, puccini being my two favorites as composers and luciano pavarotti, sherill milnes, placido domingo being some of my favorite singers
 
The two most recent Sieges Even albums are very serene. Imagine sailing across futuristic clean oceans in a kind of transcendental or quasi-transcendental world; that's kind of what it makes me think of.
 
Portishead... And just discovered Daudi Baldrs by Burzum, all "orchestral" (synths) very dark, but very transporting as well. Feel like you're a ghost in a dead castle...
 
You guys listen to some dark fucking relaxing music.

Eluvium, forgot about them!

I often like happy chill indie/electronica for chilling out.

Stereolab
Sweet Trip
Zero 7
Thievery Corporation
etc

As for metal when I want to relax I like "Souvenirs d'un Autre Monde" by Alcest, it reminds me of greenery in the British Isles.