Don't think about it for another second - BOOK IT NOW! You will not regret it. This is your chance to get a truly authentic Paris experience. Even if you're there to do all of the touristy things, you can get basically anywhere on a direct metro line from Nation stop (less than 5 minute walk from Marc's). And if you're just looking to lay low and cozy up some where, this is also the place to do so. Plenty of cafes and restaurants within walking distance too!
Laurence met us when we arrived to let us in and show us around. You will have everything you need and more. Seriously. Do it!