Another note would be that if she is getting this built from scratch,:

- in-walls beat in-ceilings
- if she wants them to be super stealthy and in-ceiling, build some good quality boxes for them and affix them to the joists before the drywall and ceilings go in. It'll make the sound way better.
- can't say this enough: Cat5e or cat6 (or fiber, I guess) everywhere. It's worth futureproofing.