Loudspeakers with a wide sweet spot

Any OHM Walsh speaker (largely omnidirectional).

Also Gallo Ref. 3s.

Blue Circle Pennies also. These are designed to go closer to walls.

Also some Dueval, Morrisons and a few other lower priced omnis.

"In general achieving a wide sweet spot I find comes at the price of imaging and detail"

Hmm, I'm not sure that is necessarily the case.

I do agree about planar designs though, Maggies for example. The sweet spot is very small.

Better omnis I've heard, like OHM and mbl, certainly do not have imaging and detail shortcomings in their sweet spot however the sweet spot is much bigger and amenable to listening from various locations in the room than other designs, in particular when it comes to imaging and detail.

Omnis I've heard are way different though in how they do imaging. But I find their imaging is just different than conventional designs, not inherently better or worse in general. Some will like it and some not, same as with any good piece of gear.

"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.