. . . I'm considering turning the top of the dome into the theater but I'm not sure that a dome shape would be good.
The dome is shaped as follows:
- 35' in diameter
- 15' high to the top of the ceiling (center of room)
- Wall is straight for first 5', then begins curve to the top.
Would this make a good theater room?
In general, it's a bad idea.
A concave surface creates a focal point; energy will be hyper-concentrated in at least one area of the room, and markedly different in other locations. That's why deep-space telescopes, satellite dishes, etc are made in this shape . . .
If one must have a concave boundary, you can get away with it
IF (just a rule of thumb here) the focal point is at least 3x the farthest distance you are able to get away from it in the room.
. . . OR if you make the dome surface extremely absorptive, to eliminate focus effects.
example: Domed ceiling with a 30' radius is acceptable if the ceiling is no more than 10' high at the peak. This places the focal point of the dome well below the 'floor', so no focal point effect will be experienced in the room - it lies beyond the room boundaries.
The classic "igloo" shape is bad, as the height and radius are about the same.
Your case sounds borderline; you'll need to figure out what the radius of that ceiling actually is. If it has a compound (variable) radius (parabola, catenary, etc) you'll really need to figure out where the focal point(s) of the curve(s) are.
When in doubt, avoid it altogether, or treat the ceiling with aggressive acoustic absorption. a "dead" room can be okay for home theater. If stumped about what to put up there, let me know.
It is do-able . . . but only if you know what you're doing!!
-- Mark