This site says that the slogan for France is "Rendezvous en France."
However, when I look at the official French tourism website, I find the equally lame "Be Inspired. Be in France." -- that's the version for the UK. The US website does not have a slogan, but promotes the awful video that I already posted elsewhere. The UK site also has the slogan "Paris is a party" inspired by the Hemingway book The Moveable Feast, whose French title was "Paris est une fête." This was used a lot right after the terrorist attacks of November 2015.
Some of the national slogans are entirely valid, though. I know that Thailand has been using "Amazing Thailand" for at least ten years. The Canadian slogan is also valid, according to the official website.