Reader Q: What's your favorite modern city, and why?

A: Do I have to pick just one? Otherwise, it's a tough question -- like Will Rogers said about people, I've never met a city that I didn't like. And while modern cities share a lot that is similar, they still each have their own personalities. Los Angeles is big and sunny and spread-out; St. Louis and New Orleans have all of those rich traditions; New York is fast and compact and endlessly diverse. I've been lucky enough to spend a lot of time in New Delhi, and I think that Bangkok is great with its swirl of royal architecture and the pulsing life of the river that runs through it. Nanjing is elegant, Tokyo is vibrant, and Mexico City is a place that I'd love to spend some more time.