Are the other two Rose and Al Sev? I trust they're all having a good time in Slytherin House. Or maybe in Ravenclaw. Gryffindor would be toooo boring, especially with Sev's idiot big brother around, thinking he owned the place.
my opinion: (no offence meant) Albus: Gryffindor (because he is Harry in a way and he'd go on believing that this was important to which kind of person he became, Harry-ish thoughts...) Rose: Ravenclaw (because Hermione's brains have been inherited!) Scorpius: Slytherin (because Slytherin can be good to and in the beginning he was a classic Snake and after meeting the other two, he realized what the real things in life actually are)