caveat: i don't really do true "ambient," i do more more soundscapey stuff (loosely) that's incorporated in multi-tracked recording or live improv of a slightly "electronic-ish" bent. . .
so, whether i'm doing a live or recorded project, the aesthetic holds true: i'm trying to place parts and textures in the stereo field. (i tend to think antiphonally, like orchestra parts complementing each other, etc.)
I'm not sure I do true ambient either, but I like loops bumping up against one another, etc.