Wow, I hadn't checked back in a while, and I see there are a bunch more responses to my thread. Thanks for all the feedback, everyone!
We would be staying with family in a city in South India (Kochi) in the winter (Christmas-time). FWIW, DH's family is quite well off and live in modern, clean housing with servants that spend their day boiling water and ensuring safe food. I would think there are excellent hospitals, etc., nearby, but I will check with my FIL (a doctor) to be sure. I've been to India twice during that time of year; both times, the family took excellent care of us and we didn't get even remotely sick. We will not be traveling, eating out, or exposed to tons of mosquitos (I barely remember any, and mosquitos looooove me). We would stay put in the house largely, and family would come to us. If I'm not breastfeeding, I can bring plenty of jarred formula/food with me -- so Baby's food will be tightly controlled.
It sounds like I really need to talk with a pediatrician (I like the idea of finding one of Indian descent) about timing this best to make sure Baby has all of his/her needed vaccines and can safely take the important medicines. And that will make my decision for me.
It sounds like 5 months is a good "travel age" for most babies, so that is nice.
As for the rest of it ... I appreciate everyone's thoughts and things to think about, but after reading the responses, I still believe that vaccination is the only thing that will really factor into my decision. DH and I are pretty laid-back about the rest of it, and I doubt that will change -- but we won't book tickets until after Baby is born just in case.