Paris in July
I heard that all Parisiens were kind of rude but I was proved otherwise. Right when we got to the city, two different people came to offer advise with direction without even asking. Also lugging suitcases around metro stations, we got a lot of help from the locals. Bonjour and merci, au revoir will get you far. :) Reserve at least two weeks in Paris if you want to see all the sights (Louvre alone is 16 km of art!). A metro card is really useful when getting around the city.
Insider Tip:Download a Paris metro map on your phone, it's a life-saver! I used both the Visit Paris by metro app (by RATP) and the Metro Paris Subway app (by Presselite). Both were good and also gave route suggestions. Most importantly, they worked offline! The five zones Paris visitè card will get you to and from Charles de Gaulle airport as well as around Paris and even to Versailles!