Audiophile Series seven π loudspeaker

Where you have no corners, I might suggest that you use an Eminence Magnum driver in a suitable enclosure below the midrange and tweeter shown above. I have plans for those too, if you're interested.

One advantage of corner loading is that it forces a radiation angle of 90º. You can see in the photo above that the midrange and tweeter also have this pattern, so this reduces reflections. When the woofer is placed in or near the corners, room modes are equally charged. Also, since all sound sources share the same 90º radiation pattern, the reverberent field has an equal distribution of frequencies and sound is uniform and natural throughout the room. This not only helps make the "sweet spot" larger, but it also makes the sound more balanced within the sweet spot.