Aussie bloke, he's right, you need to tell us your position to get a "going rate". However below I give a rough outline of what your expenses would be, based on my own experience. Please note there will be others who claim you can live cheaper than this (eg by using local schools, not having a car) but I am basing my estimates on the lifestyle you say you want;
3-bed condo - SGD3-3.5k pcm
school fees, uniform - SGD1.2k pcm
car lease, petrol, ERP - SGD 2k pcm
utilities, telephone - SGD0.5k pcm
food, groceries - SGD2k pcm
entertainment, meals out - SGD1k pcm
Thats about SGD10k pcm in costs. To cover that you need to look for a package offering around SGD140-150k pa pre-tax, assuming your wife doesn't work.
Hope this helps.