I'm looking for certain songs (or entire bands) that revolve around a sort of mysterious, astral sound. It's difficult to describe, but if you want to hear an example of something sort of simular, listen to 'buckethead - whitewash'. The songs have to be at least mostly guitar, thus radiohead doesn't count, nor is it melodic enough for me to count.

Anything you guys know of like that?
Porcupine Tree maybe?

The song Up the Downstairs (as well as others) sounds like what you're after.