Best room treatment

My large listening room, roughly 21x14, with a peak 12' cathedral ceiling, has a full wall of windows on one side, a floor to ceiling brick fireplace wall in the back, and a flimsy wallboard wall opposite the windows (due to pocket doors).  Wood floors, rough cedar ceiling. Floor to ceiling bookshelf on back wall. I knew my acoustics were severely limiting the quality of sound produced by my very expensive system but I wanted immediate gratification improvements.  Fortunately my listening room is off limits for aesthetic comment.  I intended to do a short term experiment on the cheap, and I did.  $200 in one inch acoustic foam squares from Walmart covered both side walls, floor to ceiling.  I hot glued them to windows, stapled them to wallboard so very easily undone.  Black egg crate 2" thick mattress pads cover critical parts of the brick wall.  They are easily shifted for maximum effect by drilling tiny holes in the brick grout and using finishing nails to hang.  Minimal throw rugs, again easily shifted, help final tuning.  I'll even move them depending on the recording quality of what I've got on.  That was a year ago.  Maybe some day I'll go for something more high brow, but this low buck solution had astounding results.  For bass I have twin raised REL G1 subs to pressurize and dig deeper than my YG Sonjas will go.  Thanks to friend Dick Diamond from YG, who happened to be in town.  He used his amazing ears to help me set the RELs for the most pleasing crossover points and volume - big benefit of the REL remote controls!  I could never have done that without sound measuring equipment.  With the money saved, I invested more in component suspension which is a bit harder to do on the super cheap but is super critical with my gear and suspended wood floor.  No better advice than to experiment and trust your ears!