Any advice for transfer into Paris for an after midnight arrival? I understand that train and roissybus both go to bed before 12.00am. Help, please.

Taxi os a pre-arranged shuttle service.

Allowing for a possible late arrival and the time it takes to get off the plane and get your luggage, I'd say get a hotel for a night near the airport :

http://www.booking.com/airport/fr/CD...FQ0ZZwod6VYZJg

Some hotels will pick people up at the airport.

I agree with Kaneda, if you are getting in that late, what's the purpose of even going into Paris (and I think kaneda meant some airport hotels may pick you up, not hotels in central Paris)? Taxis have a surcharge for those late hours and you will get the worst room in the hotel, probably (if they even allow checkin at, say 1:30 am, which it will probably be if your plane doesn't even arrive until after midnight). And you won't be able to do anything in Paris, anyway.

I think you should just choose a hotel at CDG that you can easily get to yourself by walking or a hotel shuttlebus at that hour. You don't need to do anything but check-in and collapse (maybe after a good shower). You can get some good deals on Priceline for airport hotels, I've heard.

I don't think you have much choice but a taxi. Maybe some airport van shuttles work that late, but I am not aware of any myself.

We like Radisson SAS at CDG airport -- not elegant but a well-equipped business hotel. Their free shuttle won't be running that late, but it is very close to the airport so the taxi fare shouldn't be too high. In the morning the SAS shuttle will take you to the RER station starting at I believe 5:15.