transportation from CDG to Paris

The "RER B" will take you into the very center of Paris and many points in between; http://parisbytrain.com/tag/rer-b/ http://parisbytrain.com/rer-train-from-paris-to-roissy-charles-de-gaulle-cdg-airport/ Cost is 9,10 Euro ($11.75) and takes 40 minutes. It's also a good introduction to the Paris Metro system, which you'll want to use anyway. Signs are everywhere at CDG & easy to follow. Buy tickets at a window (slow) or a machine (faster) when you get to the station.

A word of caution: if you don't have a chip and pin credit card, you won't be able to use the ticket machines.

We have had our hotel book their preferred taxi service, both times we have been in Paris. The price was quoted upfront by our hotel (Le Littre, 6 arron.). We just paid the drivers for the round-trips. No surprises with our prices that way.

The current adult fare from CDG to anywhere in central Paris using the RER and Metro is €9.25. Children 10 and younger ride for €6.50. There are minivan taxis in the ranks at CDG. The fare for a taxi will be around €50 (more if traffic is heavy since the meter will be running) plus a surcharge for a 4th and 5th passenger.

Kathy - If you do opt to take the RER and don't have the right CC, there are change machines near the ticket kioski's that will change 10 & 20 euro notes.

You can also take RoissyBus for 10,00 euro each; it only stops at Opera Garnier, so it's convenient if your hotel is anywhere near there, or is near metro lines 3, 7, or 8 (the lines that go through the 'Opera' metro stop). Those metro tickets would cost 1,27 euro each if you buy a carnet of 10 tickets. (click on the link within the link I've given you for a photo of what the bus looks like and other helpful info!)

Kathy , ,for five people a taxi will be not much more then the RER and less hassle. Do the math,, 50 euros on RER ,, and possibly having to then transfer to metro , walk , carry luggage up stairs at metro station etc etc( although the metro ride cost is covered with your RER ticket) .. Taxi will run between 45-55 euros.. and take you door to door. There is a 1 euro fee for each piece of luggage though( not your carry ons), and 3 euros for extra people over 3 , so that will likely make taxi costs about 60 euros. So while RER will run a bit cheaper,, the cost versus hassle should not be underestimated,, especially after a long flight .
There are taxis that take 5 people ,, you just in the taxi stand line and there is someone who will direct you into a van sized taxi.

Kathy, In addition to RER / Metro or Taxi's, you could also have a look at some of the Shuttles. There are listings in the Guidebook for reliable services, or you can check the net. Happy travels!

Thank you all for your thoughtful recommendations!