When we moved into our current home, all I asked for was control over the "family room", which is 21x21x8. Which I got, the wife give me complete control over the decorating and media in this room and all I had to give up in exchange was any iota of control in every other room. Thankfully, at that point in our marriage, I understood, trusted and liked my wife's tastes in decorating. So, it was a win-win as far as I was concerned.
In the end, I got one large room with two separate systems. If you click on my systems and take a look, I have to warn you that the room has been changed since those photo's were taken and the layout now is much more 2 channel audio friendly. I hope to update them soon
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To answer your question, if you can have an audio set up in a generally occupied and functional room with as few audio compromises, I think that would the preferred action plan.
But, at either end of the spectrum and forced to decide between cave or no cave, I would vote cave.
John