Let's get right to the point here. OP why didn't you offer a pic of the room you're trying to optimize? That would have been helpful and much more productive. Here are two things to keep in mind that are mostly universally accepted: 1-you can over damp a room with absorption 2-you have to work really hard to over-diffuse a room. With that in mind, try some different treatments and see what works for you.
Sonus Faber just updated their Homage line (Amati etc.) and they said that they are becoming more and more software modeling dependent. Look around YouTube and you will see some cool interviews with the designers and understand their process to get optimal sound. It's software driven.
The same can be done to optimize a room. The big treatment co's like Viacoustic and Artnovian will take you room specs and recommend exactly what you need to optimize your room. I took that route and am very, very pleased with the results. I don't buy into what some have said in the thread about just moving furniture etc. I guess they're not math fans. Sound waves are math. Start there and them tweak it to suit your ears. Everyone hears things differently. Good luck and cheers.