it's worth taking a look at where the airport train stops, and then find a hotel near the stops, like Gare Du Nord and Luxemborg. I stayed at a place where must change trains form Luxemborg, and it was a bit of a hassle lah.
But the Latin Quarter is a lovely place to stay, so many places to eat, and very accessible to all the tourist spots (if not, near the metro).
BE WARNED!!!!! There are MANY pickpockets in Paris, and I cannot emphasise this enough as i've seen them with my own eyes a couple of years back. When I went back last year I didn't see any, but it's worth being careful
Also, near Arc Du Triumphe, there were some mainland chinese ladies who tried to ask us for "help". It's a complete scam. Don't trust them!