Last year we took the Metro from Gare du Nord when we arrived on the Thayls train. When we left Paris on the Eurostar, we took the city bus from Gare du Lyon. This was easier but both worked.

Just a small point - there were strange people at the Gare du Nord Metro station who tried to help us buy tickets using the machines. The man persuaded us out of the ticket queue and were insistent that he could do it for us. We were equally adamant that we would do it ourselves. Then a second man came over to help after we got rid of the first. Avoid them! Don't know what their game was though!

Here's an itinerary finder for buses and the Metro. You might check if there is an easy bus route. http://www.citefutee.com/orienter/itineraire.php

An FAQ for Paris transportation. http://tinyurl.com/oy4e

Frances Toronto, Canada