For my summer job, I took my students from Spain to Boston's Chinatown for a Chinese Dim Sum lunch. None of them liked the food, but it was an eye-opening experience since they said they don't have Dim Sum in Spain.
Boston's Chinatown is one of the biggest in the US, but smaller than San Francisco or NY. I recently visited Chinatown in Honolulu, HI and apart from some Chinese owned lei and flower shops, there wasn't a very good variety of shops or restaurants and overall was a bit more seedy than I expected. For example, at lunchtime we saw an Asian girl(?) standing on one corner decked out in clothes that made no mistake she was a prostitute. At that point, I realized how good Boston's Chinatown is. It can seem a little seedy, but I would never expect to see prostitutes so openly out on the street in the middle of the day. Boston's Chinatown is a little more family friendly. It has a great variety of Chinese, Vietnamese, Korean, Thai and Japanese restaurants. Presently one of the most hyped Japanese restaurants in the country, O YA, is located on the outskirts of Chinatown close to South Station's bus terminal. It is where you can get a $20 piece of sashimi that reviewers say is worth it because of the intense, intricate flavor. I don't know about the food inside, but I did walk by it and it has a very interesting entrance door, big and wooden like a castle from the middle ages.
One of my favorite restaurants in Chinatown is the Vietnamese sandwich shop at Beach St. & Oxford St. There are big delicious sandwiches for just $2.50 each and they also serve milkshakes and boba tea.
In Chinatown there are several Asian grocery stores where you can find the most scarce ingredients, and cheap. There are of course several jewelry stores where you can buy gold and jade items. And there's even Asian fabric stores for making Thai dresses, Asian salons, Asian martial arts schools, and probably many more hole-in-the-wall places I have not yet found. It is really a treat to explore Boston's Chinatown. Even though it is not geographically that large, maybe 6 blocks, the population and storefronts are packed in to those blocks densely.