Mario Party 8 definitely. The game is a blast when you play it with your family. We are four at home, my parents plus my sister and me and we have spent countless hours on playing Mario Party 1-5 together.
Also, when the original Mario Party was released, I was about 12 years old and I often played it with girls in my age back then because they really liked it too, so I think this will please those girls definitely.
The only problem with Mario Party is that it is not really funny when there are less than four people, but when there are six family members, four should be available often enough the play the game.