Front speaker placement, trying wider placement.

Wrong on both counts. Place them where you like them but they should sound best at an equilateral triangle and pulled out of the corners and walls. 

My room is 12' x 16' and I started with the equilateral triangle positioning. It was almost perfect from the beginning. I only had to adjust toe-in, rake angle and move speakers a couple of inches away from wall.
Then add some absorbion in the corners.

Some speakers are designed to sit in the corner, but very few.

If the speakers are good enough a wider stance makes sense, and seems to be working better at this point.  
Sound fills the room more broadly, stereo twp channel sound has a nice projection from center. 
I think some are abit neurotic about toeing in and eqidistant speaker placement.  

Putting speakers in corners is not for me. However,if it works for you,then set them up wherever they sound best to YOUR ears. You are going to have to trust your senses no matter what us keyboard jockeys say. Who am I to question what you hear? 

Many like to place mains on each side of flat tv. Too me this seems to limit spread of sound throughout the room. And limits so called sweet spot to a one chair position. If u are are hermit this may work but many coexist with others and spreading the wealth seems more comfortable.

problem is mains are so damn heavy that its tough to move them around. At least b&w speakers have ‘wheels’. Also speaker cables can be too damn short. I got 12 footers.

Part of it is the compromises you are willing to make. Most of us want the best possible sound as system owner. So widening the sweet spot will reduce the sweetness of the spot. Having a reflectiveness of a flat screen will confuse the imaging. While the equilateral triangle is a rule of thumb, my experience is that optimal sound is achieved about there. Unless, you are running some odd kind of speakers like Ohm Walsh.

Sweet spot size?  Interesting.

anyone ever measure it?  Would you share with a significant other if only 2 feet wide?

all about dispersion.  Need to get some twine and build a twine enclose sweet area.  Will there be a shareable space?  
Many seem to buy only one chair for listening area.  Are spouses welcome to a listening session?  

Keep out of the corner, or the speaker in the corner will seem louder compared to other if not in a corner. 
 I placed large pillows behind the corner speaker, helped a lot! Took the boom and “louder effect” out.  
   12 feet apart, toed in a bit, 15 feet to my listening position on couch.  Works great for me. Large vaulted ceiling room. 
 Sure my Vega D-9’s sound and fill the room a lot more, but my small-med size towers sound so much better.

Check out Acoustic Fields. He just posted a new YTV that you should find very helpful
https://www.youtube.com/watch?v=f7RRIlFPE1Q

The wider stance moves you forward in the venue and makes the listening position more critical. Moving your head just an inch will corrupt the image. You also dramatically decrease the volume or power at the listening position as it drops off at the cube of the distance. The B+Ws are not directional so you need absorption on both the side and front walls as well as the ceiling or you will be missing detail and again corrupt the image.

So b&w create lots of reverbs?  They do fill room with less of the narrow focus that other spkrs may have.  
Moving head one inch to change sq seems absurd.  Very poor speaker design if true.  Too little dispersion seems awful.

@tweak1, not a big fan. I think his thinking is more aimed at studio situations. He talks as if all loudspeakers are the same and they excite the room in the same fashion. This is definitively not true. There are many speakers that are not omnidirectional that can be placed close to a wall without ill effect. He believes in putting subwoofers in the middle of the room up on stands or hanging from chains trying to avoid "room gain."
Solid floor and walls are essential in a listening room. Subwoofers are 6-9 dB more efficient in corners which means they do not have to work as hard lowering distortion. Frequency response anomalies can be best managed by room control. Low E on a bass guitar is 40 Hz. Just because the room pushes 40 Hz up 6 dB does not mean that the harmonics and side bands which tell you what kind of bass instrument you are listening to, are up 6dB. If you have a lot of harmonic distortion sure but, that is another problem a good system should not have. I get the sense he is selling his expertise and acoustic treatment.
I love the room he uses as an example, the one the client uses for "storage." It has every acoustic treatment known to man stuffed in there.
Fortunately, It is being used as an example of what not to do.