I reckon kids are very trainable, you just have to be firm and consistant. The problem comes when the visiting children arrive. The AV/Stereo problem is certainly tricky. I don't have this problem, but a friend solved this by building a false wall behind his speakers so he could set everything in the wall and close curtains over it all when listening to music. Even during movies this is better than having a TV protruding into the room. The overall cost was probably not much more than an antique armoire.
Where do you put your TV/equipment?
Most armoire & entertainment centers are big, tall, flat-sided things that sit between the main speakers--not good for your image! I want an open-architecture stand, but I have a soon to crawl kiddo who would use it as a jungle gym! So what do I put my TV and gear on/in to keep it out of reach and not destroy the image I work so hard to get?!