Check Citadines Paris Saint-Germain-des-Pres where the Wellesley-in-Aix students stay in Paris: 
53 ter, Quai des Grands Augustins, 75006 Paris
Metro: St-Michel

Also check out the FIAP:
FIAP Jean Monnet 
30, rue Cabanis 
75014 Paris

The official site of the Paris Convention and Visitors Bureau: has information about lodgings, including Furnished rentals and Apartment exchange, as well asrestaurants, exhibits and lots of practical tips (e.g., transportation, telephones, markets).
Housing Tips:
If you are seeking long-term housing (one year in general, and by law at least nine months for students)  check out, and ask everyone you know in the area to let you know if they hear of anything. Apartment hunting is competitive and often word-of-mouth is the only way you'll find something. Beware of rental scams on craigslist and other sites; even Wellesley alums have fallen for them! You can find links to news articles about the scams, and there's this site:
Orly Sibony '10
February 20, 2013 
Sabbaticalhomes is a good site and vrbo (vacation rentals by owner) is another. Most of us ignore the one-year and 9-month rule, by the way.Many people rent their homes when they themselves are on vacation, so the rental period might be a month or so.