As your kids are a bit older, they’d love the Go Ape-type setups (but better than Go Ape – far more fun), the white water rafting, canyoning….it’s flipping ace. The goat village is (quite literally) the s***iest place I’ve ever been to, but has to be experienced. There are huge numbers of excellent walks.
One of the best family days we’ve ever had was the ride up from Chamonix to L’Aiguille Du Midi (not far from the summit of Mont Blanc), then the crossing to Italy on the aerial tramway. Stunning scenery, just awesome. When you cross back, you then have a meandering 2/3 hour walk to the Me De Glace, where you walk inside glaciers, (and you can sneak off and climb down the via ferrata to the main glacier surface). Funicular railway back down to Chamonix, then back to Morzine. An expensive day – probably €350 all in for the four of us (the tickets are unsurprisingly not cheap, but you look at the engineering and you can justify it), including fuel, food etc.
Eating out is expensive, but self-catering obviously doesn’t have to be.