How old are your kids and whether your other half is fairly active?
We’ve been there with kids but they were 4 and 2 at the time so there wasn’t much for them at that age (the attendants on the lift stations were even dubious about them going up to altitude). There is swimming pool in AdH and swimming pool at the bottom of the mountain in Bourg d’Oisans. There are ice caves which are worth a look at Les Deux Alpes.
There’s still snow up high at Les Deux Alpes – so there’s still skiing going on.
There is a go-ape style place in the valley (shut out of season). We found some Via Ferrata but health and safety somewhat laid back – basically “here are your harnesses, pay when you get back, see you later”….and the cables on the rock faces weren’t that taught, so you’d likely need a rope to recover yourself if you fell and ended up dangling on your harness.
The Megavalanche race(s) themselves are worth a watch and all the riders come through AdH on the main run.
However, its probably more fun doing the Mega with other riding friends tho, cos there’s a lot of queueing to get to the top of the mountain, and I dare say it could seem a lonely place if you’re on your own and at all intimidated by the thought of the mass start and the rest of the race 😉