I would mount the LS on the wall between the window and the corner where the wall pushes out and mount the RS on the wall opposite. The LR and RR can be mounted on the back wall above the Bar.
For the record, I don't like to have my surrounds mounted very high, maybe 5 or 6 feet high. Due to my room, I have to have my surrounds mounted between the top of door frames and the ceiling. More often than not, I find the surrounds more distracting than pleasing with the sound coming from up near the ceiling. Try to keep them around ear height when standing, more or less.
Good luck. It looks like a nice HUGE room. Pics?