While the estate has obvious advantages for load lugging ; if you're going to be doing much distance with three large-ish , and still growing , kids in the back , I'd seriously look at a LWB S Class .
I can only compare my W124 estates with my 500SEL , but I wouldn't want to cram three adults in the back of an E for too long , with knees against the backs of the front seats , when the space in the back of the S offers sprawling room and significantly greater comfort .
Perhaps worth dragging the whole family to the dealers and see how they all fit in ?
S Class will have a decent boot , and for vino trips , put a box on the roof for luggage so you can fill the boot with vino .