I worked temporarily in Mexico City and almost bought an apartment there, so I guess I have a very different point of view. I wouldn't go to any of the resorts or especially the cruise ports, mostly because they don't appeal to me, but also because it's where I would view myself as a target.
But I am completely comfortable in (nice parts of) Mexico City, even with kids. I take Uber everywhere including from the airport, I stay at a stunning Airbnb, I eat at nice restaurants, I go to the playground. It's a major city, a busy airport. Parts of it are very, very wealthy. If you're a target to get kidnapped, you know why. That's not me.
I've talked a lot of families with kids into trips to Mexico City over other urban destinations. It has a lot to offer, and without the baggage of the rest of Mexico. If you're going to visit some museums and kids' attractions, Mexico City is hard to beat.
My wife a $30’000 watch wearing very recognizable Cartier jewelry. Wearing jeans and t shirts. No problems. There is not once city in Mexico that I would attempt that.
I wouldn't wear a 30K watch on the street in any major city, but that's a city thing, not a Mexico thing. And actually there are parts of Mexico City I would feel safer wearing that than any city in the US. At least in Polanco, security is obvious and the 30K watch is the cheapest one.