We are travelling to Hanoi in September. We are looking for a kids friendly hotel, well situated and with a swimming pool. Would you have any recommendations?

You can consider Army Hotel. Read good reviews about it. Has a nice big pool, family rooms and two-bedroom suites available if I'm not mistaken. It is near tourist attractions such as the National Museum of Vietnamese History and the Hanoi Opera House. http://armyhotel.com.vn/