Agreed, its far harder to get the sound pressure and manage reflections in a square room.
I placed my staircase on the short side of my room and made cut outs for my gear. When ever I want to get to the back of a unit to change cables etc I just open the door under the stairs.
REW is great. Ceiling height is also important.
I did a lighting box in my room and with hindsight I would have left it out. The more 90 degree angles you have the more surfaces you have to treat