A nice and ( for paris) spacious appartment between the 10th and the 2nd arondissement. Good connections, about 20 minutes walking distance to the gare du nord and about 30 to the Seine. And..- there's a velib bycicle "station" right in front of the door. Do try them- we found it so much more interesting and entertaining to cycle instead of using the metro. The city has done a lot in recent years to improve conditions for cyclist, though it is perhaps still advisable to avoid rush hours and busy thoroughfares :).
About the appartment: we liked the high open space and the big windows, and it was wel equipped and pretty quiet. Some stairs to climb, but nothing we did not expect.