You will have a very difficult time, for one, getting even response between the two speakers, from any given seating possition most likely. With the long wall placement(probably ideal in your senario..although you can make short wall placement work if careful), you can both get the speakers in the same symetrical/acoustical locations in the room, (potentially, as you didn't mention complete room symetry, nor openings, doors, windows, etc), equa-distant from the boundaries, and also find the same for your seating possition in relation to your symentrical speaker set-up.
Another issue is that you'll definitely have to be much more concerned about potential wall reflections near the speakers, as you will otherwise DEFINITELY be dealing with the problem of hearing the reflected sound off the wall at very close intervalls to the dirrect sound from the speakers!...bluring the immage, focus, and soundstage!!!
So, you'll likely end up with a great challenge in getting one speaker to sound the same as the other in frequency response(causing soundstage and phase shifts, etc) from most potential seating possitions between the speakers. And, you'll end up with some rather inherent acoustical reflection difficulties!
My experience suggest that pulling off a workable "corner placement"(and I've done 1000's of systems over the years) is better suited to smaller mounted satalite/sub systems, where you have greater placement flexibility! With two large stereo floorstanders, it's a dunting task to pull off well. Infact you potentially risk the sonic overall integrity of your system, bringing it down in overall quality level, simply by poor speaker placement!
If you have to compromise, and must alleviate the existing "long wall" set-up, because things are crouding your room too much, may I suggest even downsizing your system to more manageable sized gear instead! You might find that with even smaller floorstanders, or especially small monitors(and or sub set-ups), that you can keep a more "sane" "non-room-dominating" set-up, and still get great sound!...it's always compromise in the end.
Good luck
Another issue is that you'll definitely have to be much more concerned about potential wall reflections near the speakers, as you will otherwise DEFINITELY be dealing with the problem of hearing the reflected sound off the wall at very close intervalls to the dirrect sound from the speakers!...bluring the immage, focus, and soundstage!!!
So, you'll likely end up with a great challenge in getting one speaker to sound the same as the other in frequency response(causing soundstage and phase shifts, etc) from most potential seating possitions between the speakers. And, you'll end up with some rather inherent acoustical reflection difficulties!
My experience suggest that pulling off a workable "corner placement"(and I've done 1000's of systems over the years) is better suited to smaller mounted satalite/sub systems, where you have greater placement flexibility! With two large stereo floorstanders, it's a dunting task to pull off well. Infact you potentially risk the sonic overall integrity of your system, bringing it down in overall quality level, simply by poor speaker placement!
If you have to compromise, and must alleviate the existing "long wall" set-up, because things are crouding your room too much, may I suggest even downsizing your system to more manageable sized gear instead! You might find that with even smaller floorstanders, or especially small monitors(and or sub set-ups), that you can keep a more "sane" "non-room-dominating" set-up, and still get great sound!...it's always compromise in the end.
Good luck