I had a system layout almost exactly like yours about 2 houses ago! The house I moved into next was perfect for audio. My same audio system took a monumental leap in imaging and clarity with nothing more than a room change. Night and day. Reflective surfaces smear sound and don’t allow you to crank up the volume.
Your biggest problem is your room. And I know you probably don’t want to hear any of this...but no amount of money spent on speakers can fix it.
You have a pretty room but will not do so well with audio. Would be better if the entertainment system was against a short wall but I understand that the short walls are not ideal either as one long wall opens up to other rooms. Still there are simple things tou can do:
My advice is to start with a bigger, heavier rug. About 4 to 5 times the size of your current one. You can run the rug under your couches. Put the rug on a heavy felt rug liner. It will save the rug from dust mites and moths in a way that rubber netting slips can’t do.
Running the same floor tile up the wall is a design faux pas. Maybe take that down and replace with an acoustic wood texture (wood slats etc.).
Use curtains on the windows.
Put some art on the walls but nothing with glass. Exposed canvas paintings are great...wood carvings...textile art...you get the idea.
In a room like that, the improvements will be subtly accumulative.
An acoustic ceiling treatment/tiles might be the strongest solution. Something between your listening position and the speakers.