There are so many opinions on how high to mount a screen, I don't think there is ONE correct way. It really depends on how you setup your room, and how you sit when watching movies.
I like to recline a little when enjoying movies, and don't want to sit upright. I originally measured my eye height when reclined slightly. So I put my screen at a height so 1/3rd up from the bottom of the image matched this measurement. It worked ok, but the people in the back row had issues looking around the heads of the first row viewers.
I currently have my screen raised so when reclined slightly in the front row, my eyes are at the bottom of the screen. This is the most comfortable position, so I don't have to look downward, and the people in the back have noone in the way.
I do like your idea of possibly hanging the screen from the ceiling. Most screens are pretty light, especially if you build it yourself like I did, it would easily hang from the ceiling trusses.
Depeding on how deep your room is, this may work well. You could move it up high enough that the front of the speakers would be below it or sit flush with the front of the screen possibly. If you don't have a deep room, you maybe able to move it up enough to be in a more comfortable viewing angle for the viewers.
