We got a Wynnster Anglesey earlier this summer - it was a special deal, but still expensive. We liked the Vango Aspen, but didn't like the 'bedroom' arrangement. There is a larger model, but that would be truly huge. You want a roomy tent for a family, but don't get one for, say, 10 people, if you'll only be 5 as the people in the tent provide the night-time central heating and it could get chilly.
What I think is important:
A sewn-in bathtub groundsheet. Loose ones ruck up, dirt and mud can get in around the sides, and even relatively light rain can flood in.
As large a porch as you can manage, with side flaps. Whenever it rained we cooked in the porch, sometimes we ate in it as well. We stored all our boots and shoes there, as well as the washing up gear, and went barefoot inside the tent (which helps keep it relatively clean).
As large a living room as you can manage. When you're enclosed in a tent, even one child feels like a horde. With a big enough main space you can sprawl, play different games, even play physical games, which is crucial if the weather is cr*p.
Anything else is on the 'that would be nice' list.
Dh is 6'3" and could comfortably stand upright in the living room.