Speaker set up for more than 1 person

Yes, as I have said above, the toe-in approach is, at best, a compromise, but, there are few things that can be done for what the OP is hoping to accomplish--it is crazy to suggest buying different speakers, for example.  

I recall that there was one commercial model of speaker specifically designed for the time/intensity tradeoff to widen the stereo sweet spot.  It was a speaker made by Leslie, the same people that made organ speakers that spun to create interesting effects.  There home audio speaker line was not a commercial success.

@lonemountain 

Yammies

Yes l got it wrong from memory…NS8 and NS10 were the boys. Tannoys were great speakers and l remember the Lancasters were as big as radiators. I never heard a really decent sound from their smaller models, but even those were not really small enclosures.

l agree with your Acoustic Energy history.
The company hit the high point with the AE1. A revolutionary redesign for such a small speaker which should never (on paper) have sounded that good. Blind tests provoked a shock when auditioned, listeners thought they were far bigger speakers. Metal woofers with a long throw made them extremely fast and concrete bracing inside the enclosure made a bold statement sound wise. They also go very loud without distortion or harshness.

The company earned its reputation on the back of this model and has tried to emulate the AE1 Mk1s initial success. It is not the same company as it was back then, but their active speaker has had very good reviews.

The AE1s have to be heard to appreciate what was achieved. The sound from such a small speaker less than one foot high and 8 inches wide was previously thought not possible in the 80s. It was no surprise they made it into many recording mixing rooms in the UK 🇬🇧 

If you were to be honest about 3 comfortable legit sweetspots that are not compromised......Multichannel - 3 concentric driver TAD standmounts for example, where one serves as a substantial center channel.

Or there are some high end pro audio speakers like Meyer Sound that have design tricks w.r.t phase characteristics, etc (if you were to try and stick with stereo)...

You will need to fine tune side wall treatment, etc.

In summary, it probably won’t be cheap, any additional sweetspot can get expensive.

I have my system set up perfectly for a single person sweet spot. Near field about 9 feet from my speakers. But if I move even slightly off center the soundstage moves and one of the speakers dominates. If I have a couple friends over how can I arrange my speakers so we can all get a good soundstage with centered imaging? Move my speakers closer together? 

You really need omnidirectional speakers to pull it off... like MBL. 

So I went with the extreme toe in and it works pretty well. After much experimentation I have my speakers firing at the opposite ends of my 3 person size couch and the people sitting on the ends still get a stable stereo image across the soundstage and the sweet spot is completely unaffected. Looks crazy but it works!!