My visit was in 2012, so my infos are not up to date. I'm sure that booking a flight for months in advance will help getting a cheap ticket to Paris from anywhere in Europe.
Caen or Rennes airport can be a good choice, but usually flights to local airports are a bit more expensive.
But Rennes has a good connection to the the Charles de Gaulle airport, so if like Kris said someone can pick a prospective visitor up in Rennes, that'll make travelling a bit easier.
Mmmmm, butter cakes and cider!
