paris

Take the RER B to Port Royal for 10 euros Get off and take a taxi to the exact address.

If you say what the exact address is then it would be easier to pinpoint exactly where you can get off and connect to the metro.
And this trip would still cost you 10 Euros

Otherwise you pay about 60 to 80 Euros for a taxi
Try to search for yourself
http://www.ratp.fr/en/

The flat taxi rate would be 55 Euro. Go from the official taxi rank. RER is cheaper, but if there's more than one of you, plus luggage, late at night, etc, taxi might make sense for you.

Where on Ave du Maine? Denfert Rochereau might be the closer RER stop. This street runs right by Gare Montparnasse, so taking Le Bus Direct might be an option as well.

22 avenue du maine

Aéroport Charles de Gaulle 1 RER B to Saint­ Michel Notre­Dame 3 stops 35 Mins
Get off

Take Bus 96 (direction Gare Montparnasse) to PLACE DU 18 JUIN 1940 ­ RUE DE L'ARRIVEE 7 stops : 8 min
Get off

Head South West on Rue de l'Arrivée (160 m)
Turn left (30 m)
Turn right on Boulevard de Vaugirard (40 m)
Turn right on Place Bienvenüe (130 m)
Arrival on Avenue du Maine
22, Avenue du Maine, 75, Paris
(Oh yeah I stay in IBIS Hotels all the time it is good quality for the money. There is no chain like it in the USA).
Hope that is not to complicated but just 10 euros from the airport.
Also if you have a smartphone you should have no problem with google maps.

Le Bus Direct Line 4 will take you from CDG to Gare Montparnasse, but on the opposite side from the Hotel Ibis Tour Montparnasse. You will have to walk around the front of the station and cross the street and walk 300 feet. Cost is 17 EUR, but your luggage is in the hold under the bus and bus does have wi-fi.

By RER, get off at Denfert Rochereau change to the No 6 Metro (direction Etoile) to Gare Montparnasse.

First offf , taxis from the rank at the airport now charge a flat fee.
50 euros to any address on the right bank , and 55. Euros to any address on the left bank. This is new this year so anyone telling you otherwise is not aware of this obviously.
secondly , when you give an address in Paris it is far more helpful if you give the area code with it , it will tell us the arrondissement you are located in , ie of address is 22 avenue du maine 75002 means you are in the second arrondissement and therefore on the right bank. Knowing which arrondissement you are in will be very helpful to you too.

Taxi is worth it after a transatlantic flight , -especially if you have a lot of luggage

I think the second poster corrected the taxi pricing and 22 Avenue du Maine is in the 15th. It is the Hotel Ibis Tour Montparnasse which is most definitely on the left bank. 55 EUR.

Although some of us would be quite comfortable taking the RER "B" from the airport and then Metro, after a long international flight and in a jet-lagged state, Taxi is probably the best and easiest option. As mentioned earlier, there's now a flat rate of €55 to the left bank. It would be a good idea to have the hotel name, address and postal code listed in French to show the Taxi driver. You might also want to have some Euro cash on hand to pay for the Taxi.

We have used the RER all the time and find it is not a bid deal with luggage.

One thing about doing that, after exiting CDG, be very aware of pickpockets. Men, have your wallet in a money belt or neck wallet. Pickpockets are terrible.

Taxi, especially since if I recall correctly, KPen is traveling with two other people -- that makes it a little more than 18 euros a person for the 55-euro total fare. And believe me, it is worth 8 euros (per person) over the price of the RER not to have to take the RER and instead to get delivered right to the door of your hotel.

Question, what is the main train station I would leave from to travel to Amsterdam by train.

If you are booking your train ticket from Thalys, then it departs from Paris Gare du Nord to Amsterdam Central.