I'll give you my numbers:
Rent: 28k (Tung Chung, new building ~1000 real sq ft)
Schooling: 18.6k (6.2k x 3 kids in one of the local private schools)
Live-in Help: 12.4k (5k x 2 for 2 live-in, 2.4k for one part-time)
Groceries: 10k (spend on average 2.5k week)
Utilities: 4.6k (3k electric, .5k gas, .4k water, .7k internet / TV)
Taxes comes to about 15% of your gross, but you can deduct 132k for your wife (assuming not working), and 100k for each child off your gross income. My wife works so the costs do not impact us as much. But honestly, it is the air that is doing me in. My littlest was at the doctors office 10x last year with 'colds'.
You could probably save some by living in Caribbean Coast, and being judicious with your A/C in the hot months. If your wife does not work, you could save on your helper costs, but you get the idea.
It's a decent place to live, but harder since the girls came along and our days our numbered I can feel it. I've been here over 10 years and lived in all different neighborhoods, but with kids Tung Chung is pretty good. I like that I can come and go as I please unlike when I lived in Discovery Bay.
If you're confident you can land a role back home in 3-5 years, I would recommend it--as long your are certain of your expenses going in. It's a decent base to travel around to the region, and your kids will have friends from all over the world and they can take some time to learn Chinese to put them ahead of the kids back at home when they return.