Click, first congrats on your speaker purchase. Are these speakers broken-in?
What is the construction of your space, walls, floors, ceiling height etc.
Is the space an open concept, if you wish you can send me some pics showing this privately.
You are going to have fun but be patient and try different positions yourself to see, well to actually hear the differences.
Don't forget that your speakers sound can be modified by changing the pin locations on the back, what are they set up at presently. There are so many variables, you should at some time have a good read to learn and at the same time experiment to actually hear the differences. You will find that you will be able to customize the sound to your own likings and for example if someone is over for a listen and prefers more midrange, different bass, tweeter you will be able to accommodate very easily but all that's for down the road as it will just be too much for right now.
What speakers did you have prior to these and where did you find the optimal location to be and why, what did you learn about that specific space with your past speakers.
You don't have to have these 9ft from the side walls but if you could say 3ft to tweeter should work fine, this just assists in eliminations of those side reflections. Back wall I would not recommend 2.6 ft, what you could do is place them there. Listen for a week and then when your wife plans to go out move them out further to experiment, you will notice a difference in the stage depth etc. but in the end it's your call in what you prefer. What is the MAX you could get away with from the back wall and still be WAF, same goes with the side walls.
I was fortunate enough to just put them in the same foot print as other box speakers I have had in my room in the past, the sound was marvelous from the get go, that being said I did still move them arround to hear the differences but in the end preferred that original foot print. That original foot print I had learned allot from prior speakers so it greatly assisted.
Regarding putting them in the middle of the two rooms, humm I guess you could try but will be shocked if it works out sounding proper.
Your electronic position, no issue where you plan on putting them, I personally just prefer shorter speaker cables and feel the end result is superior. These speakers are bi-wired so you are going to have allot of wire especially if it is a long run.
A friend has a pair which I assisted in setting up and his living space is 12ft by 18ft and speakers are on the short wall, recently made some changes in location after he heard mine again.
Placement now 4ft from tweeter to back wall, 2ft 8inches tweeter from side wall which leaves 6ft 8inches between tweeter to tweeter toed in so the MBL logo just below the tweeter is facing just off the shoulder. His sitting arrangements vary as he just moves the chair.
You have allot of space, 19ft 5inches aprox. wide by 39ft deep aprox.