ok, I'll bite
Hard to tell from your post what you are getting after...
Do you plan on combining the 2 channel room with the family room (knock down a wall)
Or do you plan on using your previously 'no one is allowed in here but me' room, and letting others enter it?
I had a similiar quandry as you, given space constrictions. My solution was to buy this device called a Niles SPK-1 speaker switch (Amazon approx. $110USD).
I use it to switch between the AVR and the tube amp, and the sound goes to the same set of main speakers.
The AVR looks after the 7.1 channel sound, and the Tube amp looks after the 2 channel sound. The nice thing about this set up, is you can use the same source components. i.e I have the blu-ray multi outputing to the AVR in 7.1 analogue, and it has stereo outs feeding into the tube amp, this way I can listen to usb stick music, or network, or CD's or SACD's through the tube amp. When it is family movie time, all I do is turn on the AVR, the Niles unit switches sources based on what is powered on.
I do not like how it behaves with the above, I find I am risk averse, so I just unplug the power to the Niles switch, and it defaults back to AVR, with no risk of two amps trying to feed the speakers at the same time. Did it by accident a few times, and speakers were fine, just being paranoid.
I was actually quite ecstatic about being able to do this, and I have noticed no sound issues with using the switch, mind you, you are having champagne and caviar, while I am on bread and water. So you may be able to hear something that my equipment is not resolutiony (my new made up word for the day) enough to hear.
But from what I read, this may the easy solution. Your best choice, as I explained to my wife last nioght would ber to buy a house with a wider basement to accomadate all the speakers...she laughed at me