I really enjoyed staying in Maubuisson and Fourcy years ago during my first visit to Paris. All three MIJE hostels are very conveniently located in the charming Marais, withing walking distance to the Seine, Notre Dame, Hotel de Ville. Inexpensive, clean, quiet accomodation in renovated historic buildings. Great option for budget travellers.
This is a great place to stay if you're on a budget in Paris! Hostel prices but AMAZING location. Walking distance from the Louvre and right near the Saint Paul metro stop. Rooms are nice and the building is old and very pretty with a central courtyard.