The 15th district of Paris offers multiple interests.
It is first of all a residential quarter with a special atmosphere like a village in a city. Life is pleasant here. Many cafes, restaurants, shops, small stores, markets and certainely the largest number of squares and small parks in Paris.
The 15th district is also the place where the most important Parisian exhibitions are attended thanks to the exhibition park of Porte de Versailles : Paris Expo. Next to the park, Le Palais des Sports greets shows and musicals all year long. It is also in the 15th arrondissement that you can find the aquatic center Aquaboulevard de Paris and the sport center Suzanne Lenglen or famous hospitals such as Necker Enfants Malades or Institut Pasteur.
On the north-east of the 15th district stand the Gare Montparnasse railway station and on the west side, along the Seine river, the business area of quartier Beaugrenelle.
Thanks to public transports (metro and buses) you can reach the heart of Paris within a few minutes only.
As you can understand, there are many reasons to book a hotel in the 15th arrondissement. Anyway, as it is very close to the city centre, some travelers stay likely in the 6th or 7th district more famous and more touristics but also more expensive. Staying in a hotel in a residential area like the 15th district with so many attractions and connections can be a better experience than staying in some more famous places.