The best room treatment for me was done by accident!
My parents had a very dense hand-woven wool rug that they didn’t use anymore. Cost them around $5-6k and is beautiful so I didn’t want to get rid of it. It was nearly the size of my listening room so I put down a large felt pad on the wood floor and then placed the rug over that. It replaced a basic polyester rug that covered maybe half the floor. Immediately the sound softened and its was just the listener and the speakers.
Otherwise chairs and a couch in the room, but this rug seems to have stopped reflections very effectively.