Hi NerdBrain, I would consider using a pair of in-ceiling Invisa HTR7000s as your surround speakers. I would also consider mounting them in the ceiling directly to the left and right of your main listening position. I'd also spread them apart (within reason) as much as you can and directing them toward the main listening position. This would produce a convincing surround effect while minimizing the amount of sound going into your daughter's bedroom. Looking at your room layout, this would place these in-ceiling HTR7000s approximately 6"-9" away from the back wall.

From a performance standpoint, the MPXs mounted into the back wall (around ear level) would also work well, but the sound heard in your daughter's bedroom could be a problem. It's also difficult to use a backbox with the MPX's 3.75" mounting depth.

If you can use the SuperSat 3s mounted toward the back corners of your room at ear level - and angled inward, this would also work well (without much sound being heard in your daughter's bedroom).

Later on, adding a set of Invisa 650s as your front Atmos speakers - mounted slightly in front of the main listening position (and spaced closer together than the Invisa HTR7000 surrounds) would produce a convincing Atmos effect. Happy Listening!

Awesome, thanks for the feedback! I just spoke with my local retailer/installer and he also suggested going the HTR 7000 route rather than the MPX's, so that seems like the best option for my situation. Thanks again everyone!