Stay in the old town itself — not in the beach resorts ten minutes away. The old town transforms at night in a way that only works if you are already there when the change happens. The bridge lights come on, the sampans push out into the river, and the streets fill with silk and grilled spring rolls.
Eat everything
Hội An has its own cuisine, distinct even from the rest of central Vietnam. Cao lầu — a smoky wheat noodle only cooked here, using water from a specific well — is the signature. Bánh mì at Phi Banh Mi. White rose dumplings at a hole-in-the-wall on Lê Lợi. A cooking class in the morning and a street-food tour at night is not too much; it's the right amount.
Commission a tailor
Hội An has a centuries-old tailoring tradition and is the place in Southeast Asia to commission a bespoke shirt, suit, or dress at a fraction of European prices. Walk in on day one with pictures of what you want; first fitting is the next morning, final collection on day three. Do not cheap out — go to a proper shop with a waiting list, not a tout on the street.
Day trip: My Son
The My Son Sanctuary is an hour inland — a cluster of 4th-to-14th century Cham temples, half-reclaimed by the jungle. Go before 8 a.m. to beat the tour buses, and you'll have parts of it almost to yourself. It is a quieter, older, less photographed counterpart to Angkor.