A concern shown by many clients is quiet operation of whichever fan unit they are purchasing. Remote fans clearly will assist with this as the fan is not located directly above you. There are other factors that can help with a quiet installation.
For bath fans, try to get at least 5-8 feet of flexible insulated duct between the fan and grille. We have found this ducting does a great job at minimizing noise and vibration transmission.
Kitchens are bit tougher since any fan moving the volume of air that they do will be louder. Typically a Fantech Silencer will assist in this matter quite well. Distance will also be your friend on these as the fans can typically be mounted anywhere in the duct run. Also, try to get a couple bends in the pipe between the fan and the kitchen. This will help bounce the sound waves back to the discharge side, and help keep things quiet.
For those of you doing general ventilation, boosting your HVAC airflow and other tasks, you can use a combination of the above and use a couple of the following:
If you are trying to boost airflow at a particular register, try to keep the fan back from the register by a few feet if possible.
Those with rigid duct would do well to replace a section around the fan with flex duct to help absorb some noise.
The use of a speed controller can help quiet a fan as well. You can purchase a fan with a little more power than you need and dial it back to suit your need.