You'll have to google for the full information on both programs I suggested. They have excellent reputations, but it comes down to how you learn languages best. The Sorbonne and Alliance Française programs are a little grammar-intensive for me. Then again, I learned French as a child with an aural-oral program (listen and repeat) that is more like something a Berlitz would offer.

When I first came to France, I did a month of intensive French classes as the Institut Parisien - however that was 15 years ago and the school has changed hands and location since then. It was great (IMO) when I was there, but I have no idea if or how it may have changed since.
Cheers,
Bev