I have a very similar room size to you and I've been back and forth on long wall/short wall placement for years. After all the experimentation I've determined short wall placement is best. There are two problems I have with long wall placement, the first is that I'm too close to speakers for the drivers to properly integrate. Second, there is way too much energy going into the long wall opposite the speakers, these reflections destroy the sound. Treating this wall with absorption drains the life out of the music. On the other hand, long wall placement gives a wonderfully wide soundstage.
I, like Cuwill keep my equipment low to the ground on two equipment racks in order to not negatively affect soundstage, this also enables keeping cables short.
I also manage to keep the widest possible soundstage by placing my speakers even closer to side walls (about 18" to center of drivers) and pointed straight ahead. This is closer than most suggest, but in my case dipole speakers (very little sound energy to sides) and mucho room treatments make this work very nicely.
I will never mess with long wall placement again, nothing beats firing those speakers down that long open space, natural diffusion is key!
I, like Cuwill keep my equipment low to the ground on two equipment racks in order to not negatively affect soundstage, this also enables keeping cables short.
I also manage to keep the widest possible soundstage by placing my speakers even closer to side walls (about 18" to center of drivers) and pointed straight ahead. This is closer than most suggest, but in my case dipole speakers (very little sound energy to sides) and mucho room treatments make this work very nicely.
I will never mess with long wall placement again, nothing beats firing those speakers down that long open space, natural diffusion is key!