Family Drama
Imagine that your whole life is about your home. Imagine that's your life because you're from an immigrant family (or a family with immigrant roots) living in sub/urban America.
Of course you're going to have family drama: there's nothing else to focus on then the minutiae of everyday life, whether it's Mrs. Sen and her problem with driving, or Mr. and Mrs. Das bickering about whose turn it is to take their daughter to the bathroom while on vacation in India.
Then there are Shoba and Shukumar as well as Sanjeev and Twinkle: couples who are dealing with the problem and possibility of creating a new family together. Couples who find out that they really don't have matching visions of what a family should even consist of (kids? no kids?).
The only family without drama? The family in "The Third and Final Continent." But that's only because we see everything from one point of view—the husband's.
Quest
There might not be any knights and holy grails in this book, but there are plenty of characters in search of … something. The narrator in the last story isn't exactly on a grand quest: he just wants to live the American Dream of a house and a stable family. He gets that dream without too much trauma, but he's a rarity in the book. The other characters in the book end up having to suffer various forms of loss in order to achieve their goals. To have a family of her own and be cured of her illness, Bibi ends up having to experience abandonment and then rape. Miranda has her first major heartbreak in order to gain some self-respect. Mrs. Sen doesn't even get what she wants (her fresh fish); instead she gets into a car accident and loses her babysitting job.
Quests aren't easy; they're full of obstacles and few people survive unscathed, even if we're only talking about places as tame as an American suburb.
Coming-of-Age
Coming-of-age stories aren't just for or about kids. Sometimes adults need to grow up too. Like Shukumar or Bibi—both of them act like children who still need to be taken care of; that is, until they're forced to grow up. In Shukumar's case, Shoba tells him she wants to leave the marriage; in Bibi's case, a rape and parenthood force her to become self-sufficient.
Growing up, no matter how you dice it, is painful business, especially for the real kids in the book—Lilia and Eliot. Lahiri shows us that becoming an adult can involve coping with absence (Lilia loses Mr. Pirzada) and loneliness (Eliot loses Mrs. Sen).