I'm flying into Paris later than I wanted to (plane lands at 9:15pm) and will be staying near the bastille metro station. I know I need to take the RER B and then transfer either at gare du nord or chatelet les halles, but I read somewhere those are two stations you might want to avoid late at night (and probably when you are jet-lagged). Also, if you need to buy a ticket using a credit card, will it still work if you don't have a european credit card with the smart chip? Are there change machines, since I read the ticket dispensers don't take bills?
Alternatively, I've read that I can take the Roissybus to opera and take the metro to bastille from there....do you think that would be easier/safer?

You can buy your ticket with cash at the ticket office at the CDG train station. Easy ride on the RER B to Gare du Nord with a quick change to metro line 5 for Bastille. There is six times less crime underground than on the streets of Paris, in case you are wondering.

Or you can take the Air France bus (even if you don't fly Air France)to Gare de Lyon from where it is only one subway station or walking distance to Bastille.

Where the Air France coach stops, is just down from the taxi stand that is straight outside the main entrance, i would take a cab that time of night, as you should not have any trouble in getting one, and the Bastille Metro is only a few streets away.

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<hr>I read somewhere those are two stations you might want to avoid late at night<hr></blockquote>
It seems to me that if you are afraid of getting mugged in the subway, you are far safer at Chatelet or Gare du Nord since there are always lots of people around. The same goes for any of the big hub stations.

I stayed near the Bastille last weekend. Gare du Nord can be very very crowded, but you can find help there (even in English). The small metro stations are unfriendly to anyone lugging baggage, and the ticket people can be decidedly unfriendly, unless you speak good French. I would avoid the metro if tired or with bags. An easy way to do it would be to catch a cab to your hotel from Gare du Nord - takes 5 mins and only about 8 Euros. Will save you pain and anxiety just when you are least able to deal with it. Once at home in your hotel, then use the Metro if you don't want to walk. At off-peak times and without baggage, it is very neat. The Roissybus was suggested as better than the train by some, but didn't use it. The train between du Nord and CDG is perfectly fine and quiick. Arriving at Opera still leaves you with the problem of going across town to the Bastille neighbourhood. If you have moderate to big bags, I would catch a cab. If lightly laden, just catch the metro - a very quick trip.