I was just in Paris about two weeks ago. If you you are looking for a modest and clean motel you might want to try the Bonne Nouvelle. It is located right by Gard du Nord. While not exactly centrally located there are a lot of metro lines near that allow you to get around Paris very quickly. Mind you I did walk down to the Lourve but it took 45min.

Hope this helps.

Tom Cobban,London,Canada