Room Acoustic treatment suggestions, ideas & recommendations

Recently retired and really listening to system now. Since retiring I have much more opportunity to enjoy my audio system Krell Processor and amps, B&W 803D2 speakers. Although the system sounds quite nice I’d like to improve on room acoustics. Room is far from perfect as far as treatment is concerned. Room dimensions are 15W’x23’Lx8’H. The problem I face is that it has 4 large windows (4’X6’) along the length of one of the long walls along with an entry door and 2 windows (4’X6’) along the short wall in back of listening position about 10’ behind listening position. Windows are covered with only 1" blinds.The other long wall is interrupted by an 10’X8’ opening to the rest of the house which I am contemplating closing off with heavy velvet drapery that can be opened or closed. Floor is hardwood with 8X10 thick pile area rug, furnishings are heavy upholstered Couch and recliner, coffee table, 2 corner desks, a lot of wall decorations where possible, Large 2’X2’X6’ tower CD rack and of course the audio equipment. Behind equipment on wall are 3 - 2X4 Heavy wool area rugs and various hangings.

This room is dual purpose Audio only and Home theater.

I am thinking of placing some bass traps in the corners along the back wall as I noticed some standing/reflecting waves at the back of the room. I am also thinking about Draping off the side windows with heavy velvet drapes from floor to ceiling to reduce the 1st reflecting points. For ceiling reflective points I am thinking of sound absorbing panels suspended from ceiling. I’m also debating fabricating some removable diffusers to place in the window openings behind the listening position. They of course would need to be fairly light for removal as I do not want a permanently installed diffuser. (any suggestions on how to construct a light weight diffusor). Does anyone here have any thoughts on my plans? Suggestions, Opinions? All input is considered valuable.