I just got back from a weekend in Paris, and thought I'd contribute my experiences. Traffic is heavy throughout the city as many people opt to use their own cars to get about. Similarly, quite a few empty Velib stations, if that's how you were planning to get about.

I had no trouble getting a taxi from CDG into the centre of town, but getting taxis in town is more tricky. We waited nearly an hour to get a cab from our hotel in the 13th to Gare du Nord, after two cabs refused the journey. Due the heavy traffic, finding a cab that's willing to take passengers to CDG is virtually impossible.

Cab lines have stopped taking bookings, so you really do have to take your chances. Whatever you do, leave plenty of time to get out to the airport, both on account of the heavy traffic volumes and the difficulty of finding a cab.