Incredibly beautiful room! If I had my pick of rooms on this site, yours might be it.
The Stradivaris are awesome speaks, but I would love to hear a pair of good omnis in your particular room.
Ever consider Ohm, Morrison, Dueval, MBL or German Physik?
There's a system on this site with a multi story room like yours. That listener (with deep pockets) went with German Physiks, which to me was a very insightful approach. Good omni designs should really shine in a large room like yours and enable optimal listening from multiple locations as well.