Fantastic idea. I've actually made two paris weekend runs (IAH->CDG) this year. On the plane ride over I'm always thinking "am I crazy" but when you are sitting in that little cafe and sipping on an espresso, the thought "paris is always a good idea" comes through pretty strong.

its pretty easy to get to downtown from the airport - just ride the train into les halles (hope I have that right) and from there get a cab or stay in the system to get to your hotel/etc.

window shopping is always great in paris. just the thrill of walking around is very cool.