If you go to India for the B737NG then I would suggest Jet Airways. They offer a pretty good pay package, housing allowance, travel benefits etc. Your time off is paid. Spicejet has no travel benefits, lousy HR department, no paid time off, and unstable roster. I think they are offering 3 year contracts. Many expats at Spicejet have left to join JetAirways. You can expect to make around $8500/month with another $2200 for housing. You will need the entire housing amount and more if you want a nice place in Mumbai or Delhi. Jet Airways base is mostly Delhi. Your wife should feel safe in India. Crews are respected but remember you are a contract pilot and don't expect long term employment. Once you are not needed, out you go. No seniority, no retirement benefits.
China seems to pay more and many westerners prefer China as it is much cleaner than India overall, and infrastructure is better. But you are in a communist country, remember that even as you see a McDonald's down the street. You can be fined and docked pay for hard landings and can be thrown in jail if you have an accident.
Best would be to make a short trip to India and China and see for yourself.