Canon is one of the few climbing areas that you can access on foot when coming down from Paris by train. Not many people do that these days, but it's cool to know it's an option. Just walk straight across the forest from Bois le Rois.
There's lots to go at, and it holds a lot of people, with no shortage of pleasant picnicking spots in clearings between boulders. The most popular Girl Problem is likely Le Bombé (assis droite) 7a, which wins not from being overly pretty or climbing particularly nicely, but by virtue of having all its climbing finish within 5 feet of the nice flat ground. Ditto for Babaobab 7b, which has the added advantage of small holds that suit strong little fingers.