Here are 4 pretty good relaxing songs that I enjoy.
"Amsterdam" - Peter Bjorn And John
This song is pretty good for about anytime. It would be pretty nice if they got an actual music video for it though, it would be pretty interesting seeing what they would come up with for this song.
"Sleeping Lessons" - The Shins
Not joking at all, I sometimes use this song before I go to sleep. So relaxing and makes me a little sleepy after a little while when I want it to. The music video is pretty random, but its good nevertheless.
Black Hole Sun - Soundgarden
The music video may be as creepy, seriously, creepy as fuck, but the song makes up for it. The guitar and drums go together pretty well. I listen to this sometimes when I am feeling a little down.
Young Folks - Peter Bjorn and John
Yes, Peter Bjorn and John again. The whistling is VERY catchy, usually doesn't get out of my head for awhile. I like what the song was going for with a nice casual beat.
Feel free to tell me other relaxing songs you know of, I will be interested in em :).