My current house was chosen for its price and location. It just happened to have an area for my system that is the best I have ever had.
17' X 22' plus pony walls to kitchen and hallway, that increases the open area with an additional 11' X 22'.
The lanai has two large doors opening to the main room giving some "breathing room" of an additonal 14' X 22'.
Vaulted ceilings are 15' with the peak inside the the main room a few feet.
The lanai walls are only screen and all windows and doors in all this area are always open. (Even though it is a neighborhood, I check with the people nearest me and they say they don't here my music. Maybe they are all hard of hearing.)
I went minimal on equipment after decades of many pieces and some quite expensive, but this is the best sound I have ever had in my own home.
Still, the Big improvement, most recently accomplished, cost me nothing except my own labor moving hard and soft surfaces and changing adjustments that the speakers have built into them.
Having this hobby for 50 years, it can still be surprising what rooms and room treatment will do.
Again, this home was purchased because it was a bank foreclosure in 2010 and it was exactly the area we wanted to live. Luck on both accounts.