I have decided to back off from building my theater with 10 foot ceiling due to the position of the screen/projector and how far I would have to mount the projector from the ceiling. I am thinking of going back to the original plan of 8 foot ceilings. The bottom two rows will have frames that measure 32" x 22". With the first two rows occupying 44 of wall height the larger frame will be 32 x 50 for a combine height of 94 leaving 2 at the top. Crown molding will be installed around the entire room to hide that 2 gap.
Why did I select 32 wide frames? With the 2 x 4 studs on 16 centers I wanted to make sure that each frame was backed up by a stud.