Don't stay there. It will take you at least an hour each way to get into Paris, which makes it inconvenient to take a nap to work through the jet lag. You'll have to pay to take the train from the airport into town and be subjected to, um, some of the less savory elements of Parisian society. I am a serious Marriott aficionado, and even I wouldn't stay there unless I had a compelling reason to be near the airport.

Paris has scores of charming hotels that will give you a much better experience of the city. My favorite hotel for price & convenience is the Hotel Hospitel, located on the top floor of the Hotel Dieu (public hospital) at 1 place du Parvis on Ile de la Cite, about 50 yards from Notre Dame cathedral. The train to the airport stops right under the hospital, as does the Metro. Yeah, you may share the elevator with a couple of nurses and a guy on a gurney, but the people at the hotel speak English, the rooms are super-clean, the price can't be beat (about 86 Euros per night), and the location is unbelievably good. Their website's kind of hard to find, so send me a private message if you want more info. I have other recommendations if you want something a bit more romantic.

Paris = Good choice of destination for Valentine's day, IMO. The weather may be lousy, but it makes smooching your sweetie in a cozy cafe that much more fun.