@bipod72 Good post. I much agree with your point about making a comfortable space. I will also be using my new dedcated listening room as my den/office.
I've had two dedicated listening rooms and I'm presently building the third. The first one I designed from scratch for a new house, and the second is in my current house which is a repurposed bonus room. I'm building a new house now so I have the opportunity to design and build my third dedicated room.
My current listening room is fairly large (35 x 17 x 8.5) but its dimensions are far from optimum. It's upstairs so it has a floating floor. It has wall to wall carpet and no specialized room treatment. The walls and ceilings are standard construction. I have my components on racks spread against the front wall and the speakers sit out in the room 6' from the front wall. One wall is Ikea bookshelves full of albums, books, and tchotchkeys. My CDs are in several dowel racks that tilt each row of CDs up (good diffusion). My desk and computer table are in the back of the room along with other furniture. I have a leather listening chair, a turtle shaped leather ottoman, and a leather couch. There is a coffee table, lamp table, egg chair, and other furniture. I haven't put up system photos on Agon because its so cluttered and messy that I'm embarrased when I look at other member's rooms that look like they came out of an audio magazine ad.
The reason I'm going into so much detail about my current room is that it sounds fantastic. I've had a few other audiophiles listen to my system and they all have been very impressed. The guy who sold me my Thiel CS6 speakers told me that if they had sounded that good in his system he wouldn't have sold them. The overall point I want to make is that this room defies most of the conventional wisdom about listening rooms but it sounds wonderful. In fact, it sounds better than my custom built listening room from my previous house that had all sorts of specialized construction details like stand-off brackets for the drywall and sat on a concrete floor. I had treated the room with absorbtive panels as well.
For my new project I decided to relax and not worry about audiophile listening room "wisdom." The floor is standard, the walls and ceiling are standard, and I'm going to cover the floor with typical carpet.. The one area where I will do some heroic things is the electricity where I will have a dedicated 100 amp service and several 20 amp circuits just for this room. The room is 19 x 29 x 9 so I've got quite a bit of room.
My plan is to decorate the room with stuff that will provide absorbtion and diffusion. I'll keep my CDs and albums in the room and I will put my desk, computer table, sideboard, and other furniture in the back of the room with my stereo equipment and a TV monitor in the front. Basically the room will have a lot of stuff all over the place which will provide natural absorbtion and diffusion and serve to break up standing waves. If I end up with sonic problems I will consider commercial sound treatment as a final step.
In preparing for this project I've read quite a bit of material and watched more YouTube videos than I care to admit. I've seen several audiophiles report the they built a new room using audio construction techniques and their rooms sounded horrible when they were done. Then they had to spend large amounts of money on commercial sound treatment to get things right.
I don't want to oversimplify things but the single best indicator of your listening room is the slap-echo test. Clap your hands sharply (once) and listen for the reflected sound and the decay. Do this in several places in the room. If you do this in a variety of rooms you will get a good feeling for how this defines the room's acoustics. If the echo goes dead immediately then the room is likely too dead. If the echo goes on too long the room is too live and will muddy the music. You cal also listen to how defined the echos are. A well defined machine gun echo will be a problem.
In summary, I have come to the conclusion that how you decorate and furnish your listening room will have a bigger effect than it's design and construction. Basically, fill it with furniture and tchotchkeys until it sounds good. Take the money you save from not using fancy drywall and exotic construction techniques and buy a nice big couch. If you make the place interesting and comfortable good sound wlll likely follow.