For me going a trip with family is not just visiting the city but also spending a quality time with them. Staying at Kentaro & Kyoko's place is perfect for this trip.
we have so much time at the place but also easy to going out exploring the city.
the access to the train station is good, we always start our trip to azabujuban station in the morning, and come back home throug the roppongi station, so we always walk in the slooping road.
If you go with a group this is the good option to stay.