May I respectfully disagree -- and agree with Mike -- for the reasons Mike detailed above plus one: as your seating position varies, so will the optimum speaker placement.
As your room is large enough to allow you to avoid the usual compromises in the bass, why not define the listening position first and optimise speaker positioning based on that?
In theory, there should be one ideal placement for the speakers, all other things being equal (temperature, dB SPL, power, etc, etc, too many variables to enumerate!). Regards