If you need an apartment very conveniently located in a nice area of Paris, you'd do well to book Khal's apartment. It's right smack in the center very near Republique, with two metro stops practically footsteps away from the building.
The apartment bldg has an elevator and fast wifi. Khal was a nice host allowing me to leave my bags a couple of hours after "check-out."
Thanks, Khal!