I just remeasured my speakers and from center cone to center cone I am at 44 inches.  

Hi Jimmy, exactly why I checked mine again too. And they were around 44 to 45 inches too so I decided to try moving them closer together now eg 40 inches. And pull them also closer towards me as well by about 3 inches. It all has made a difference and I like it better now even than before. 
 
Having them 5 or 6 feet apart is just nowhere. You will just never get that lovely centre phantom image happening. When it is happening you can pan sounds hard left to centre and to right and the strength of the signal does not seem to change. That is what you should be after.
 
Things changed for me when I got a 27" screen. I like it but it does require some time to position it correctly. At first it was a little close to me and the speakers futher away (slightly behind it) so now I have reversed that to a certain extent. The screen and the speakers are on a very similar plane now. Or if anything speakers are a touch closer. It is a better sound inside the triangle. More robust, better low end coupling, louder and tighter sounding.
 
Concrete stands make quite a pronounced difference too. The sound also sounds like it is coming direct to you as well and not from anywhere else. Nothing in the room vibrates now. (I am also on a concretes slab though which helps I think) When speakers are not on concrete stands they tend to make things move in sympathy. Test this for yourself by feeding low frequency sine waves into them and feeling what is vibrating around your room. You will be surprised. The problem when things vibrate is they too become a sound source but you don't know if the sound they are producing is either adding or subtracting to the real sound in the room. (peaks and dips etc)
 
 
 

question... is it possible to have these current day monitors set in such a position that two or three people can all sit in a "sweet spot" for listening... in anyone's opinion?  Although "wide" spacing may not be the best solution, ( like 5-6ft), what would be the recommendations for using smallish, nearfield  monitors, so I could have a client or two listen to playback at the same time?  IOW...sitting beside me is preferred.
Seems the JBL LSR30X series addresses that with their "waveguide" horn lens...or whatever you call them nowadays.
So, if we're getting down to 40 inches or so, that seems to exclude anyone else after one person.
Or do I position another set of speakers, that cover a larger area... like mid-fields?

I agree that close spacing sounds great, and probably the best for using these types of speakers, but 25% of the time, I'm not listening alone.  (hand the other person your headphones!!)

I must say, as of late I've re-visited this topic to really try and find as much info as I can about this.
 
From the JBL LSR 305/8 manual on distance...
"• The listening distance can be determined according to your preference, the acoustics of your room and the
maximum SPL (Sound Pressure Level) you want to hear at the listening position. You can find the speaker’s
maximum SPL at 1 Meter in the Specifications Section at the end of this manual. Each doubling of listening
distance will reduce the SPL at the listening position by 6 dB in an acoustically absorptive room, but only
3 or 4 dB in an acoustically reflective room."

At one meter, they produce up to 112dB...so around 106+ at two meters.  ...still quite loud.
 
I could not find anything about height, but only to line the tweets up with the ears.  It appears vertical orientation is generally preferred, as it minimizes the phase cancellations caused by the separate locations of the two drivers, in a typical two way system.  However in Sweetwater's little info blurb in their "Nearfield Handbook", DEALING with mixing desk surfaces..
 
"You may want to consider a speaker placement other than the console meter bridge, perhaps on an elevated mounting arm attached to the wall, or on a mid-field monitor stand, just behind the console. These positions can help clean up that 2 millisecond window. Keep your ears open for other problem reflections, like between the sloped connector panel on the back of the console and the baffle of the speaker, which will find its way back to the mix position a bit too late to be useful."
 
(the 2ms references the reflection path, btw)
Therefore, because the especially applies to my setup (and I do it like Sweetwater suggests with the mounting arm), I'm wondering why as well, elevated speakers pointing downwards still can't be in the plane of the ear, just like the speakers are "toe'd in" to directly face the listener's position.

Btw....I did try moving the monitors around...closer, etc.. and I'm not sensing the difference of the "phantom center", that seems to be so readily heard.  The JBL speakers seem to especially address this topic with their Wave Guide "technology" and suggest the "sweet spot" isn't so confined.
Another reason to buy MORE SPEAKERS!!  :-D
 
PS...btw, the Yamaha manual for the HS series speakers didn't really address this topic, other than the triangle preference...

In my opinion, if you need to handle both mixing and multiple listeners in the same room, you may want two sets of monitors.
 
I have my mixing monitors spaced 40 inches apart and toed in at 30 degrees, which provides excellent imaging for me sitting at the desk, but they just can't provide proper imaging for the "spectator seats" 3-7 feet behind me. I would get a mix to have a wonderful image when listening at the desk, but when listening to it from the "spectator seats",  the imaging wasn't nearly as good.
 
Specifically to address this, I recently added a second pair of monitors spaced 7 feet apart and toed in at 15 degrees, and this provides excellent imaging for the "spectator seats". By the way, these second monitors are JBL LSR2308P's, the somewhat similar predecessor to the LSR308's, and I'm very happy with them.
 
I also have about as much acoustic treatment as my fairly small room can hold installed, which is also very important. And lastly, I use IK ARC2 on both sets of monitors. It does an amazing job of fine tuning my monitors to my room. Both sets sound wonderful and virtually identical to each other at their respective listening positions. Others may disagree, but from my experience, I'd say that ARC2 can make any decent monitor you may have sound extremely accurate in your room, whether you spent $300 or $3000 or more on them.