First hand experience (stories about room treatment) needed

I have a 19x15 or 20x14 rectangular room. The speakers are using the 14/15ft wall of the room. For a while, I have been working on getting rid of objects and furniture that shouldn’t be in my (but it is also our) “listening-ish” room. I’m ready to embark on another new voyage. First it was the system. Now I’m taking a little hiatus from that and pivoting over to room treatment for now. A lot of people seem to say room treatment is what I’m supposed to do next. Does anyone have a good experience to share? I know of lots of ones that didn’t go well, but I want to know more about the ones that did it, had a good experience and did it for under $______ for the whole room. Then it changed your life afterward.

I’m hopping for somewhat affordable, quality made room treatment product with no bad chemicals, good quality workmanship, and that looks nice. I don’t think it’s asking for a lot (at least it shouldn’t be).

As far as my setup, I do have a holographic soundstage that extends ceiling to floor, beyond the speakers but it stops at the sidewalls. The depth is good. It is behind the speakers to several feet back. In good recordings it all swirls right  around and is an awesome experience. I honestly was surprised to get to this point without have to do some room treatment first. My budget allows one step at a time and will keep going until either it’s starts to get ugly, or next step is exceeds my money vs sense budget/ point of diminishing returns. My speakers are out about 5’ from the front wall and a few feet from the sidewall. Listening seat is in the sweet spot that works for the audio, but also works well for the look of the room.

I’m on a hardwood floor that sounds like a drum (we are on a crawl space). I’ll tell you up front, nothing is going to be happening with woodwork to the floor. Stuff on top of the floor- no problem there. I already have a big shag carpet and a thick pad underneath it. It stops just a couple inches away from the speaker feet.

I have some echo and reflections in the room I’’d like to address and also want to treat the front and rear walls. That will be either stage 1 or possibly split into stage 1 and 2 (depending on cost). I’ll  listen for a while after that stage is done to figure out what the room needs next and continue to work on gathering the next $installment needed.

I also have 2 subs and bass response is pretty good, so low frequency would be last on the list (it also seems to be the most expensive and ugliest of them all)

Any helpful experience you can share or tips you can offer would be greatly appreciated. 

And after it’s complete, try to explain your before situation and how it was after, if ugly or ok, size/use of room, and how much you spent.