We think first of hotels as our base while traveling, but Paris is well equipped with short-term apartments for rent (flats to let).
More and more visitors to Paris are renting/letting apartments instead of staying in hotels.
Renting an apartment for a week or two is not as easy as making a hotel reservation, but the convenience of having your own place, and the cost savings for both lodging and food, as well as for incidental expenses such as laundry and Wifi, can make the rental process well worth the extra time.
Your greatest expense while in Paris is likely to be lodging. By renting an apartment, at a minimum you get more space and convenience than with a hotel room. Usually you also get a lower cost per person, per night.