Loudspeakers with a wide sweet spot

Regarding the Eidolons, I've lived with a pair for over 8 years and I'll stick by my recommendation for someone looking for speakers "with a wide sweet spot." Members of our local audio group certainly have no problem enjoying a listening session seated all across the room, and my wife, who is my regular listening partner, often enjoys sitting well off to one side enjoying the music we're playing. Yes, the holographic soundstaging is even better sitting right in the center, but the frequency balance, resolution and detail when listening well outside that center position is still exceptionally good.

While the Eidolons do have a very good measured off axis response and sound decent off axis, they are far far better when seated exactly in between with very very precise set up.

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"Omni's will also work if you can pull them far enough out into the room so that rear wall reflections do not have any deleterious imaging effects."

Good point. This is key!

Blue Circle Pennies are supposedly designed to go closer to walls.

OHM Walsh speakers are acoustically attentuated in the wall facing directions so this helps them go a bit closer (two to three feet I would say in some cases involving smaller rooms) than otherwise with true omnis like MBL for example. For larger rooms, you will generally want them out further. My biggest room is ~ 30 feet deep and the OHM 5's in that room are a good 48 inches or more out from the rear wall. Soundstage is huge (wall to wall for many recordings) and imaging is sharp and focused in most of the room situated about 6 feet or further back from the speaks or so.

Tannoy.

Gallo Ref I & II's have 270 degree tweeters. They need to be out in the room. HUGE sound stage. $1500-2000.

MBL's are 360 degree. You need monster amps also. You might find some just under 10K.

Vandersteen Quatro have a nice big sweetspot.