Morzines access to skiing is a little over rated, If you're going up the Prodains to Avoriaz everyday it's best to stay in Avoriaz, otherwise you still have to get to the prodains car which is a bus ride from Morzine, Pleney side (although a new lift) can still take ages to 'get up' the mountain as everyone piles up there first thing so can result in long queues - plus the next lift up doesn't really take you 'up' anywhere, more along towards lets gets side. SuperMorzine doesn't really access much terrain and is really only good for getting to Avoriaz (if you're going this was it's better to take prodains).
The resorts mentioned in Grand Massif, will only be ski in/out in a few places, so unless you can strike a blinder of a deal you'll still be getting a bus to the slopes.
I'd stick with the Chatel choice, by the sounds of it it was your first choice. If you've got a good chalet in mind go for it.
Or go catered and get a free minibus ride to the slopes :D
