What are the best Room Accustic Treaments members have found?

There are many great acoustic treatment companies and products out there, but one I am fond of and have worked with at some shows is Acoustic Innovations. They are American Made products, great people to work with, and have very visually appealing products. Much of what they do is theater oriented and they have an incredible client list that they can't publicly disclose.    

https://acousticinnovations.com/wallscapes

In my RoomPlay Reference room, all GIK except for corner 20" ASC tube (bass) traps that I have had for many years...
IMO, GIK is fairly priced, and they are very friendly & helpful.
No downside of which I am aware.
Best,
Jim Smith

I had a large blank wall behind my listening position and the reflection back to me was annoying.  I’ve purchased many decorative rugs in my world travels, so I bought some wooden rug wall hangers (they can be used for decorative quilts as well) and put up a 5 by 7 Persian silk on wool rug up on the wall.  Looks awesome, and really deadened the echo...

I am an avid amateur photographer and have several of my best photos printed on larger canvases (30 by 30).  They are stretched tight on a sturdy wooden frame— I buy the 1.5 inch thick versions, without a dustcover on the back.  I take Sound absorbing wool, carefully cut it to fit in the back of the canvas, and cover the back with tightly stretched and stapled muslin.  Several commercial sound treatment companies offer this approach, either with your photo, or their stock selection.  I can achieve same thing for much less, and have a better quality photo of mine on archival canvas.

i haven’t tried this yet, but I am thinking about getting some sono tubes (used for pouring concrete footers and columns), lining the inside with sound absorbing material (the stuff sold for automotive sound proofing is awesome), stuffing the tube with insulation), and covering the outside of the tube with a nice thick fabric.  Put a bottom and top on it and presto, a bass trap.