i wouldn't worry too much about the ceiling height with the esl-63.
the ceiling height in my livingroom is about 10feet, and the quads play louder then would ever need.
the most important thing, placement wise, is keeping them at least 1 foot from the back wall with a slight toe in.
they sound more meaty and bassy when placed on the floor, but i prefer the clarity and increased soundstage you get from placing them on stands.
i also found them to have quite good bass down to about 40hz. more than enough for youthfull techno music, like justice, r