Speakers with wide listening window

Totem speakers are designed with very wide dispersion characteristics in both horizontal and vertical axes.

One of the larger models may do a good job in your [large!] room.

Try crossing the axis of the tweeters somewhere ahead of where you will be listening; the closer to the speakers they are crossed the broader the area of listening but as in most things expermentation is necessary. May help, if not you have no expense.

The "listening window" has two aspects: Tonal balance, and imaging.

In order to get good tonal balance across a wide area, you want a speaker whose off-axis response is very similar to its on-axis response. This also pays dividends in naturalness of timbre and reduced listening fatigue, as it's desirable for the reverberant energy in the room to have approximately the same spectral balance as the first-arrival sound.

In order to get decent imaging for off-centerline listeners, you want the far speaker to be louder than the near speaker to offset the difference in arrival times. This is harder to get, and requires well-controlled radiation patterns and proper setup (strong toe-in). The key is that the near speaker's output must fall off fairly rapidly and uniformly as you move off-axis towards the outside, so that the far speaker ends up being louder at least in the upper mid and treble frequencies, where we get most of our localization cues from. Imaging will still be best up and down the centerline, of course.

Imho, ime, ymmv, etc.

Duke
dealer/manufacturer

Bose 901, the only way to get a wide listening window is to use a speaker that is so defuse that it can't possibly have a "sweet spot". The higher resolution and more transparent a speaker the smaller and sweeter the sweet spot. It is simple physics primarily because there is only one spot where the listener is the same distance away from both speakers.
Cheers Johnnyr

As others have suggested get a speaker with good off axis response.

Think of speakers as lights. Most designs are like a spot light. A few are designed with wide even dispersion that makes the off axis match the on axis - a flood light.

What to look for? Take a look at Stereophile frequency plots where they show the on and off axis response for various degrees. Look for a design that is even and smooth both on and off axis.

Example of good "flood light" response

Example of Bad "spot light Response

Notice how the bad response had a huge hole in the midrange off axis. This means that with this design you will only get an even response when sitting close to the speakers and in the sweetspot.