I'm not in Paris but I use these guys for normal waxing (too chicken to do a Brazilian lol!) But they're really clean and as a chain, strictly regulated. There are 14 centers in Paris.
You don't need an apt. but sometimes they're busy and will tell you when you can return (like in an hour).
http://www.espace-epilation.com/centres/
Here's another chain I haven't tried but they have a good reputation and there are a whole bunch in Paris. I think you would need a rendez-vous. Have the hotel or a friend call;
http://www.yves-rocher.fr/control/product/~category_id=10200/~pcategory=10000/~product_id=SI020/~hbxSrc=
http://stores.yves-rocher.com/france/fr/moncdb/at/search/
Perhaps you'll get lucky and someone will speak English. Actually, you really don't need it. There are different waxes at different prices so they might show you some. They can write down the prices if you're interested. Friends who didn't speak French used them with success.
I'm into supporting local merchants but honestly, I had a couple of bad experiences so I would recommend sticking with a chain, just to be sure. Plus, you didn't say where you are in Paris.
What you want is a "brésilien" or "maillot" (may-oh).
Good luck!