A perfect location! Very easy to walk to all the main sites, or catch the metro - with children of 15,14 and 11 we did a combination of the two.
You can even see the Eiffel Tower and the dome of Les Invalides from the apartment - fantastic at night when the Eiffel Tower sparkles for 5 minutes on the hour, every hour!
All in all a great long weekend in Paris. Though just one thing. If you're there on 1 May, lots of museums are closed.