Insulation and maybe 2 layers of drywall on the ceilings

When I am in my master, I expect my kids to be asleep also... so, I don't see a conflict of space. But, yes, insulation and extra drywall should do it.

What about if the bathroom is above, do you hear the "sounds" or the flushing or the shower?

There are two categories of sound transmission in structures:

--Airborne transmitted sound;
--Structure borne sound

Each type must be treated separately and based on it's own individual characteristics. Airborne sound can be attenuated with mass. Structure borne sound can be treated by decoupling the structural elements with an air space.

Typical solutions include:

--Airborne sound: acoustical batts and acoustical gypboard to increase the mass between the area of sound and the area where reduction is desired;
--Structure borne sound: use of suspended acoustical materials, such as ceilings and walls using resilient clips or similar devices.

Caution: if you don't know the type of sound problem you have, you won't know the proper solution.

Good luck with your project.

We have 2 bathrooms directly above my kitchen/dining room and if I pay attention, I can hear the toilets (only) but not the showers. It is just insulated.

One thing I think that contributes to the low sound is that toilets are only 1.5gal flush nowadays... They aren't moving 8 gallons like they used to!

Roxul Safe and Sound is a sound reduction insulation.
Drywall with two layers separated by a viscoelastic layer of glue like Quiet Glue. Although their site is down.

Here is a link that might be useful: Quiet Glue

Or use Quiet Rock, it is specifically designed for apartment building and the like as a sound deaden-er or mitagator.

I have a master on the first floor.....and I love it.

The vent stack and plumbing run in the wall right next to my master.

I don't hear the shower either, but yes, I can hear the toilet flush. It isn't noise that bothers me. The bedrooms are on either end of the house, and nothing from either of those rooms can really ever be heard in the master - and I can tell you there isn't anything special in between floors either.

For new construction there are several ways to address sound transmission. This link gives some easy ideas that may work in your case. You can search his youtube channel for more videos on soundproofing.

Here is a link that might be useful: Risinger Homes - Soundproofing

Soundproofing is VERY technical stuff. Most of the time people talk about it and have no idea what they are talking about.

The video above isn't bad, but it doesn't help much between floors. Virgil has the issues bang on though.

With what you are describing, you definitely need to pay attention to both types of issues. How much money are you willing to throw at the problem? In most cases it isn't a huge deal, though I am particularly pained by noise so I appreciate spending real cash on it.

Two layers of drywall with acoustical sealant between and a z-channel or resonant channel plus putty behind any penetrations will make the room very quiet. Basically increase the STC by 5-10, which is a huge change.

https://www.youtube.com/watch?v=-IfYuNnRLgU

Highly recommended. Plus since it isn't "firmly" attached, it can help lower the chances for random nail pops from house settling or whatever.

Insulation in the space will help, but it is NOT a major reduction, unfortunately sound just doesn't work that way. :( Stop air movement, add resonant mass, and understanding the real limitations and goals. That's the way to do it.

Oh and also concern yourself with the layout of your HVAC. You can go to all of this effort to reduce sound, only to punch a hole that directly connects between the two rooms via a big air vent. That has to be designed right as well. Maybe insulated lines, rubber disconnects (I don't know the right name, just something to allow the ends (all of them) to be soft connected vs hard) add in some bends etc.

The distinction between the sources of the sound is not particularly relevant. Structure borne sound can become air borne sound and visa versa. To reduce sound transfer it is necessary to use all three methods: mass, absorption and resiliency.

Resiliency can consist of ceiling drywall on resilient channels of various designs, various resilient adhesives and special drywall systems and a thin resilient layer under the flooring above.

Absorption can consist of thick insulation batts in the floor cavity and carpet on the floor above.

In the absence of a concrete floor system, mass is usually achieved with a thicker drywall ceiling.

One of these systems alone is not very effective so there are no simple answers to the problem in spite of what is claimed by manufacturers of proprietary systems.