What a great opportunity to have your beautiful instruments out to admire and play any time you have the inclination. I’ve frequently seen guitars and the like on display in people’s homes, but I’ve never seen violins, violas or cellos stored out of their cases because they are much more sensitive to temperature and humidity. The only exception to this is in violin shops, and the shops near me keep their instruments on display behind glass, either in cabinets or in display rooms. If you are very careful with the temperature and humidity, and ensure they are out of the way of traffic in and out of the room, I don’t see anything wrong with having them hanging up. I personally love to see instruments on display!