Ambient recommendations

[Lysander]

The following are not strictly ambient but still awesome:

Bohren & Der Club of Gore - Black Earth
Cocteau Twins - Victorialand
Clint Mansell / Mogwai & Kronos Quartet - The Fountain
The Infinity Project - Mystical Experiences
Vangelis - Blade Runner Trilogy
Ulrich Schnauss - Far Away Trains Passing
God Is An Astronaut - All Is Violent, All Is Bright
Rosetta - The Galilean Satellites
Akira Yamaoka - Silent Hill 2
Agalloch - The White EP
Sigur Rós - ( )

I would also add:

Leviathan - Shrouded by Fog
herbst9 - Buried Under Time and Sand
Raison D'etre - In Sadness, Silence and Solitude
Kammarheit - The Starwheel
Atrium Carceri - Kapnobatai
Blood Box - A World of Hurt
Asmorod - Derelict
Lustmord - Heresy
Sleep Research Facility - Nostromo

These are the very best I've come across, though they may be a bit too dark for what the OP was looking for.

I'll look into your other recommendations though.