Based on you OTL Asylum post and our PM conversation [https://www.audioasylum.com/cgi/vt.mpl?f=otl&m=38458], I believe you’re in the midst of obtaining new Atma-shpere MA-1 amps and SoundLabs.
If you room sounds ok with your current speakers, you should be ok with the SoundLab’s. Moving them ~4+ feet out from the wall behind them, should be a good starting point. Moreover, I wouldn’t worry about purchasing room treatments until the new Atma-sphere MA-1 amps and SoundLab 645’s are installed and you’ve played around with positioning the speakers and have become accustomed to what they present sonically and bring to the room – i.e. wait for the status quo to develop and be established. That will give you a better handle on what a tweak or move here or there, will provide etc…
The placement of the speakers in your drawing seems like it is a good starting point.
Although the desk may be where you’re at most of the time, it obviously should be quite secondary sonically to the sweet spot on the sofa. I would tweak things to sound their best at the sofa and be satisfied with what then occurs at the desk, with perhaps a subtle compromise here or there.
Your rear/corner bookcases appear to contain albums and books. These should help absorb and deflect the speaker’s rear wave. Heavy drapes over the window area may also be of benefit, but that sort of thing can wait. Because you have what look like louvered doors at the back of the room, enclosing a space with what looks like an angled wall, these features could quite well be beneficial.
Although SoundLab’s are physically imposing, I’ve found them set-up wise, to be quite room friendly. I would assume that is because they are line source drivers and side and ceiling reflections are curtailed. This is why they can be placed quite closely to the side walls and even ceilings.
The goal should be to have the initial sound wave arrive at your ears before its remnants. Thus, dissipating or slowing the propagation of reverberate energy, especially from the speakers rear wave, is important which is why they should be pulled as far out into the room as possible &/or sounds goods.
Good luck and congratulations on your new equipment. After fiddling with the set-up, let us know your observations and findings.