14' wide room, and the screen is only a tad bit over half of that, I'm definitely voting for main speakers outside of the screen. Final decision on that is very dependent on distance from wall. I'd personally see if there was a way to test it out. Anyway, a good starting position is 38% room length, doesn't matter front or back, tad bit less is ok, lengthwise orientation. Just whatever you do, not against the back wall, and then not exactly in the middle of the room.
