I would say Portes du Soleil.
We go every year to the same place, renting a little chalet between Les Gets and Morzine. There are so many miles of good runs and each one offers something for everyone.
There is a fantastic run my kids love, which allows them to go through trees and bushes. I will find it on the map in a minute. https://www.piste-maps.co.uk/Piste-M...teMap-2017.pdf
Also, if you get an all area pass, you can go to Avoriaz, where you can play on the two stash parks, this is great fun for everyone. Another challenge might be skiing to Switzerland for a day.
EDIT - Its called Les Choucas, which you get to from the top of Le Rainfoilly.