How much would it cost in US Dollars to live in Nice, France?

What can of job will you have, will you both be working? Health care and retirement depends on your salary as you enter the National health service and the national retirement fund. It also depends on your job category (executive level pay more than workers percentage wise for exemple). Then you can buy additional health care to cover for what the Social Security doesn't pay for. Do you want to buy or rent the house (two different kinds of taxes), are you going to ask for a bank loan, where do you want to live, outside the city where you can get a house or inside where you mostly get appartments, how old are the kids, are you going to put them in the (free) French system or are you going to pay for expensive private English speaking school? Once you have put some flesh on your dreams you can start looking for answer. But just to give you a rough idea, Nice being the third most expensive city in France if you want an average life in a rather cheap area start thinking 3500 Euros net minimum (that's around 4400 Euros gross).