The most valuable bit of French I learned for a trip to Paris was bon jour (deliberately and badly pronounced bahn-jur with a smile), which translates to, "Obviously, I don't speak your language, so can we please change to English?" without having to speak any English at all.
The only problem I had during that trip was with a couple of Brits selling wine in Paris. I forgot myself and began with "Hello" in their shop, and was read the riot act even by native English speakers. I had been warned not to do that, but it slipped out.
Good people, I was treated very well, and I had a great time. My bahn-jur was always greeted with a smile and an English response. Some of that may be because it was two months after 9/11, and there was a lot of sympathy for Americans then.