It's obvious. Cafe del Mar of course. For relaxing, any of their "Dreams" compilations or their normal volumes are good. Others would be:
Kaskade:
"My time", "What you are to me", "Tonight"
Elmara - "Training"
Koru:
"Otis", "Submariner", "I believe"
There are sooo many more. Must youtube the above.
Oh, and this one: YouTube - Aware - Esperando La Lluvia - slightly bad quality, but its excellent on a lower volume.
Godspeed You! Black Emperor, try the "F# A# (Infinity)" album. YouTube - Godspeed You Black Emperor - The Dead Flag Blues - the song The Dead Flag Blues from the above album.
The entire song actually goes for about 16min 30sec. Skip to about 1:50 if you want to skip the monologue and hear the music (although the monologue is worth listening to).
Shame on you all for not suggesting Brian Eno any sooner, music for airports ftw. Also, Massive Attack's mezzanine and 100th window albums are good to chill out to, as are Sigur Ros. Edit; also the dark side of the moon album by Pink Floyd