I'm curious more than anything...
How far in front of you are they?
Is hanging them from the roof out of the question?
The surrounds would be about 4 feet from the screen, and I would sit 4 or 5 feet back from the surrounds.
Hanging from the ceiling is out of the question for several reasons. 1) Any seating positions behind the speakers would be odd. 2) It's a vaulted ceiling with only half the ceiling in the room. High one side, low the other. 3) They would look much better mounted in the positions I've reserved for them.
For normal mounting positions, there's the entry to the dining room on one side, and a wide window covered in blackout curtains on the other side.