I will tackle the easiest question first, in all our travels CDG is the rudest most difficult airport we have encountered.
Regarding tennis,
Wimbledon. At this point you can pay an extreme amount of money to a third party specializing in providing a Wimbledon experience. Or, you can create a wonderful experience by obtaining your tickets via the Queue (which we have done). Google Wimbledon Queue to find a variety of tips on how to partake in this unique form of obtaining tickets. In our opinion Wimbledon sets the platinum standard for an enjoyable tennis experience.
French Open.
https://tickets.rolandgarros.com/en
Quite a bit more jam packed event and be prepared to be jostled about, still worthy of attending at least once.
https://tickets.rolandgarros.com/en
Tickets are a bit more easier to obtain and the site is still open for making purchases. We do not attempt to stay near the grounds, but prefer to stay away form the hustle and enjoy quieter environment after finishing with tennis.
For both events we encourage dressing in casual country club attire with breathable fabrics. We found the attire helped us blend in with the locals and felt more of being part of the experience.
You will find little similarities between the US Open and these events, especially since the food vendors DO NOT gouge your pockets and offer excellent fare. If you are an American and attend on July 4th then please wear some Red, White and Blue and learn how welcoming so many people are to you.
Enjoy!