We wouldn't use the sliding glass doors regularly, however, she who must be obeyed (the wife) wants their functionality to remain in tact. ie. I'm not allowed to plug them up or remove them completely.
As for sound leakage, it is a concern, but something I don't think is going to be completely avoidable. Something I'd like to address nevertheless...
Yes, they are cathedral ceilings. The roof line is at around 24 degrees from memory.