What was the most popular leisure time activity in France in the early 1900s (1900-1909)? I’m assuming it was the cafe and the cafe concert. But I’m not positive. Can anyone help me out with this question?
I’ll assume that sex holds a prominent, but ill documented, position. 
cycling would have been a big leisure activity at that time too, especially in more rural areas.
Tennis and fucking.
I’d guess an opiate of some sort. And alcohol. Lots of alcohol.
You forgot masturbating.
French?
Drinking wine, eating cheese, etc.?
Hmmm, I’d have to go with sex.
I would say the same activities that are most popular today: smoking, drinking, and sex (not necessarily in that order).
So, watching TV and Facebook?
Along with le hanky panky they would be playing boules, making wine, creating la cuisine, painting along the Seine, dancing the can-can, traveling. It was probably a great time, until WWI came along.
I was going to say tennis, but I believe the good Doctor has a good combination in play.