I can't remember any particular stand-out venues, but then I've always gone to the region in summer for alpiney type stuff and the valley crags have been a refuge during bad weather. Briancon itself has a few crags almost within walking distance, but from memory as you head south not only are there more crags in the valley, but you descend a little so it gets warmer (Briancon is at around 1500m I think!). Best bet is to try and get a copy of the Haut Durance guide and look for sun-facing crags that aren't too high up. For family fun, there are several good via ferrata in the area, might be an option if chilly as you can keep moving? Some of them are reported to be pretty child friendly.