Will be in Paris for theonth of July and plan to use Metro in the city and make day and overnight trips To nearby locations including Reims, Amiens, Chartres, Dijon and Normandy/Bayeaux.
What is the best transportation pass to get?
Hello Tom, Based upon what you are planning to do, I think you are best served by buying individual tickets for the train.
You could consider getting a Navigo Decouverte pass for the weeks (Monday - Sunday) you will be in Paris, or even for the entire month of July if you think you'd get enough use out of it. If you are living in one of the outer arrondissements of Paris and traveling to the center every day, it could be worth it more than if you were staying somewhere more centrally located and walking more.