Bike park stuff in La Plagne hasn’t been great in the last few years. They don’t seem as sorted as Les Arcs in that respect, but as the liftpass prices have risen perhaps this year is different. The footpaths stuff is on a par with, if not better than, Les Arcs imo, especially the stuff down to Champagny but you need to negotiate the lift system wisely or risk being stranded miles away from your base. I think there is some climbing involved to get back to the main valley from this side; I’ve probably erased it from my memory.
La Ros is Ok, nothing amazing. The Black “dreamtime” or “dreamforest” is good. I believe the more interesting footpath stuff down to Seez is off limits. I won’t be visiting this year. Just keep driving over the Petite St Bernard to…
La Thuile is phenomenal, way better than Pila, but possibly too difficult for an 8 year old especially after the Superenduro blew out the corners last weekend. Pila is lots of DH lines up top and one very long “enduro” trail down to the valley floor. It gets pretty boring after 3 or 4 runs.