We stayed across the road at Grand Balcon apt's this year & overall especially for half terms it was really good value for money. Our kids are 7 & 9 so the steep stairs weren't a problem, the view out the lounge of the Chamonix valley was amazing.
I big tip for anyone to make this work, pay 35EUR for a ski locker at the lifts, perfect no carrying skis in my case all of them! 5 minute walk, ski's on & up the lift.
In Jan you can book for £300 for the apt, so really good, wouldn't go at half term again as it was to busy & ski school classes had 15 in but they still did a great job & were very friendly. Please take note of the ski lockers!! you can book them at the lift pass counter,