Is it better to rent a private bus for weddings and events in France, or rely on local transport?

A friend of mine is planning a wedding near Bordeaux, and she’s trying to figure out the best way to handle transport for guests. Some people are flying in from other countries, others are coming from Paris. The venue is in the countryside, so it’s not easily accessible by train. Do you think it’s better to rent a private bus for guests or just let them sort out taxis and cars themselves?