Wow sounds like a challenge! I'm glad it went well!!!
I can totally relate to the 24 hour plane ride! My dh is from India and it's about the same to get there. We just went with the kids last summer. My 7yo had a great time but it was very hard traveling with a 3yo!! Especially one with health issues including a severely restricted allergy diet! I can also relate to your feeling there's nothing to do. Unlike the US, I can't drive there. There are no clean parks, no playgrounds, and the mall is very crowded and not very kid friendly. We sometimes travel around that area but it can be very complicated-- you probably know what I mean. Hotel reservations get lost, things come up. You just can't stop at the local gas station for snacks, you have to pack everything. When you get there late at night, the restaurants might not be open.
We have decided we are not going back until it's a lot easier for us to manage the kids. Like when they are way older (maybe 10 and 7). We will go in the summer because rates are a lot cheaper and we can stay longer. I wonder if it's possible for your dh to make the trip alone more often so he can see his family. That's something that dh and I talked about. We may also make arrangements to fly there with the girls when they are in their early teens and they can stay the summers and someone can fly them back to the US. That way they get the full cultural immersion.
7yo: "Mom,I know which man is on a quarter and which on is on a nickel. They both have ponytails, but one man has a collar and the other man is naked. The naked man was our first president."