PalQ

He can just follow one of the canals like Prinsengracht from near the Leidesplain area back to the train station and see the essence of amsterdam - its lovely canals lined by ancient townhouses. If he's going in May or so the days will be long so he may be returning to the station in daylight.

Intrepid1

Tell him not to avoid the five block stretch of the Damrak which runs toward the Dam Square and takes off directly in front of the station. This is certainly a side of Amsterdam that he should see as well as the more quaint parts of the city.

WallyKringen

Why don't you go with him? Take earplugs (I'm not kidding) for the loud music places, dress all-purpose city-like (as opposed to motherly or overly touristy) and be ready to go wherever, see whatever, talk to whomever, doze off at times, but have a blast.

Amsterdam is one of the few cities where the unexpected is expected and accepted - an older woman (sorry, but by comparison with a 21-year old son you must be) with a much younger guy is nothing remarkable in a place like Amsterdam. Just go and have fun and try to stay awake, then you'll both be crashing out the next day.

But do take a huge portion of open-mind attitude, Amsterdam is there for everybody and for all kinds, and I mean for all kinds of people, so leave any judgmental propensities behind and go with the flow.

WK