Maybe not a possibility for you, but I have exactly the same size room and it took me a year to figure out the the sound was way better using smallish monitors (Sonus Faber Concerto and Spendor S3/1) on the long wall, firing across the room. You end up sitting kind off close to the monitors, but soundstage is way bigger than on the short wall.
Also if this isn't possible, check out this link for details on speaker placement on short wall:
http://www.cardas.com/insights/index.html
I know I haven't said much about specific speakers, but in my opinion placement can be just as important as type of speaker in getting a great sound.
Also if this isn't possible, check out this link for details on speaker placement on short wall:
http://www.cardas.com/insights/index.html
I know I haven't said much about specific speakers, but in my opinion placement can be just as important as type of speaker in getting a great sound.