Corner placement of stereo system

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

If you are in doubt about the scenario, you can, of course, always move things around and try! however, if you want to see how differnt things really are between each speaker in that set-up, place the speakers where you want, and just measure the differences with a test tone disc and sound level meter! what you'll find, is that likely your getting more bass overall from one speaker to the next, and one speaker will read a lot different at various frequencies than the other! This leads to lots of soundstage shift and inconsistencies, and phase challenges, etc. Also, you'll still have to contend with not quite as good of immaging and immage blur from simultaneous(or close) wall freflections back to your ears, from the wall besides/behind each speaker!
anyway, experiment and find out!
have fun

I don't understand several points that have been stated by LTHKEEPR.
When I place a mirror along the wall that would be behind the speakers, the speakers are not seen because with the set-up the walls flare out with respect to the speakers/listening position, so I assume there would be virtually no 1st reflections and therefore little smearing of the imaging. Also, since the set up (speakers/listening position) is symetrical with respect to the corner and the both walls behind the speakers will be treated the same, why would the speakers have a different frequency response.

If I had a nice small system, I would just move things around a try it out; but with 250lb speakers and over 250lbs of amplifier, not to mention dedicted outlets that also will have to be moved, moving around my system is hugely difficult.

Also, BRTRITCH: What type of speakers do you use; big or little?

All comments are greatly appreciated!!!!!
Richard