The "Please Take A Seat", someone will be with you shortly" door sign can be used by a variety of businesses and organisations where there may be a waiting area for customers or visitors. 

Some examples include:

Medical clinics and hospitals - Patients may need to wait in a designated area before they are called in to see a doctor or medical professional.

Retail stores - Customers may need to wait for assistance from a sales associate or for a purchase to be retrieved from a stock room.

Government offices - Visitors may need to wait for their turn to be served by a government employee.

Service centres - Customers may need to wait for their vehicles to be serviced or repaired.

Financial institutions - Customers may need to wait in a lobby or waiting area before being called to meet with a banker or financial advisor.

Airports and transportation hubs - Passengers may need to wait in a designated area before boarding a plane or train.

These are just a few examples of businesses and organisations that may use this type of door sign to manage customer or visitor expectations and improve the overall experience.