Could you tell what was logistics for all places - how did you move from place to place and how much time/cost was it involving?
Would you go at these places again? Why (if yes/no).
Regarding mai chau/moc chau - plan to do it but want to minimize travel time.
soc son is the district where noi bai airport is. north from the airport is a hilly area. there is a monument on top of a hill dedicated to the mythical king giong. at the base of the hill is a vast temple complex. i rode pillion with friends, so cost was negligible. you could take public bus to soc son town and then transfer to xe om.
i went to a friend's village home in bac ninh countryside. vast expense of paddy fields and the ponds and waterways were filled with blooming lotuses as it was in the middle of summer. plan to go back in winter and stay in a hotel in bac ninh town itself and start exploring from there. there is a european designed star-shaped fort. there are also very old temples in bac ninh such as but thap and dau. there are regular buses from hanoi.
duong lam is an old and well preserved traditional vietnamese village in son tay. i believe some of villagers offer homestay so you can stay there overnight. we hired a car with driver and i think we paid close to a million dong for the day trip. if you go by car, you could visit ba vi which is not very far away, or attempt tam dao further north from duong lam.
it takes four hours to travel by bus to mai chau, much faster if by car. if you check airbnb, there are some very interesting lodges and homestays. hope to go there next year, stay a few nights and meet the thai people.
would i go back? why not. love the culture and history, and such places in the north are usually not too touristy
dau temple in bac ninh
see also:
https://www.travelfish.org/sight_profile/vietnam/hanoi_and_surrounds/hanoi/hanoi/1009