Hi Dave,
We had a D7 cabin on Explorer and while it was just fine for the 2 of us, the only problem I can see is all 4 of you sharing one small bathroom. There is plenty of space to unpack and the luggage does fit under the bed easily, if you can arrange some kind of schedule for the bathroom, you should be fine. These cabins were actually one of the nicest cabins we've had yet on a cruise. You all will really have a blast on Explorer.
Donna
Tuesday Chat Host