I agree with him too.
There's plenty to do in Hanoi for two days. A really interesting city - with loads to see.

Alternatively you could spend a night at Ha Long Bay. Amazing views and some of the boats really are stunning, with delicious food. Most one night trips leave early in the morning and you get back the in the evening on the following day. You could do Saturday and Sunday - though I think it would be a shame not to see Hanoi.