For 4 people, there are a few things you need to consider. One is easy access when there are mattresses in both rooms. Looks like that Duo tent has a seperate side door in the main room too, which is a nice feature.
I much prefer the shape of the Heron tent as the second room is truly a full-sized room, not just an annex. But it only has 2 doors. Still, you could have the kids in the back room - and they could still use the back door if they're old enough and need to go out by themselves - and use the front room yourself.
If you really want to be comfortable and don't mind taking up some more space, I would recommend one of those 3 room tents. Like this one: http://www.colemanaustralia.com.au/gear ... 9-cv.aspx#
I've seen another Coleman tent similar to that that I liked better, but cannot find it now. Those tents would give you a room for the parents, one for the kids and that in between room for easy access in and out of the tent and for wet weather sitting/playing. The awning looks pretty useless like most of them. I'd highly recommend a tarp over or near the tent for rainy weather. I see Diamantina has a similar model, the Drysdale, but I would be worried about the lack of windows and doors for ventilation with that one. I hate not being able to cool the tent down quickly after a hot day.
I am a bit of a Coleman tent fan and I also just love, love, love looking at and talking about tents.