There are several places where we might ask someone to sit down, such as when we extend that invitation to a friend in our home, or to a business associate in a conference room.
Of these two (which are heard rather often):
- Have a seat.
- Please sit down.
is one of them more appropriate than the other to ask people whom you do not know too well to sit and have a talk? Would one of them be more appropriate than the other in a more formal setting?