I considered an Estate car for our family but ended up buying an Extra Long wheelbase Viano and never looked back. It was definitely the right decision for the stuff we do.... So ok.. its 5.23m long but I saved lots of cash as it was cheaper.
Its so easy to drive, its near vertical sides and tailgate makes it easy to judge dimensions. The front drops off quickly and I think its a but dificult to judge the front - but thats me. Reversing seems to be easier for me!
We have a young family too and its so easy to lift and buckle kids in from the inside as there's tons of headroom and leg space. Sliding doors means it easy to get kids in and out when parked side by side in car parks. The other perks are that you can get to the kids easily without having to get out of the car - just go straight through the middle fron the front. And if it rains, with the tailgate up, you have shelter. Buggies don't need emptying or collapsing, they go straight in, even with all the seats in. If you're potty training, plenty of space in the van, they don't need to get out.
I'm lucky to have a friend with a Vito with 2 bench seats that I can swap with my 4 individual recliners giving me a total capacity of 8. We had it fully fully fully loaded up to the Alps and Italy with snow gear, buggies, cots, etc... etc... no problems.
Other than that, its been really useful to me for van like stuff, carrying bikes, snowboards, kayaks and towing other things around.
If there's one disadvantage, the bigger car you have, the more stuff you carry!