For that size family I would definitely be leaning towards the Ram Megacab dually. We love ours. As mentioned earlier the rear seats are super comfortable and recline. There is a huge amount of room behind the rear seats as well, enough for small suitcases. And the legroom is huge; my seven year old son can walk from one side of the cab to the other with ease. The Megacab DRW has the same GVWR, axle ratings, and trailer tow ratings as the crew cab DRW as of the 2013 model year.
I find I don't miss the 8' box as much as I thought I would. And the Megacab dually looks sharp and is quite rare; I have had far more compliments on this truck than any other I have ever owned. Lastly, the Cummins with the reliable CP3 high pressure fuel pump is the icing on the cake!