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SQ_Blaze is spot-on.
I also like to aim speakers 90-degrees away from the first side reflections on the walls, this way the side reflections are the 90-degree off-axis response which is essentially zero output, and this makes the walls disappear. I like that the speakers are less sensitive to the room in this way and I find them more accommodating to otherwise non-ideal rooms.
Also I find I want more cone area in the lowest frequencies because my baffle size is not large enough to keep the rear wave from interacting with the front wave at my listening position. So I'm using a pair of ported 12" subs in addition to the four 10" woofers on the towers in addition to the 8" midbass drivers.
I'm a bit of an open-baffle convert.