For a taxi, there will be a supplement charged for the 4th person (around 3 euros, I think). With 4 people and baggage you would need a minivan type of taxi such as an Espace. Otherwise, I think someone in another thread mentioned a good experience with a shuttle company for about 60 euros. It may be easier in your case to simply take a shuttle rather than take your chances on an appropriate-sized taxi being available.