If a two bedroom DVC is within your buget, then that would be the way to go.
When our four kids were younger we stayed in the cabins at Fort Wilderness. It was nice to have the bedroom (with a double bed and bunks). You could close the door and not feel like you had to go to bed when the kids did. The kitchen was nice for a quick breakfast, so you're not wasting money on the younger ones who eat so little anyway. We slept on a Murphy bed in the living area (standard mattress...not like a sofa/sleeper!) They are very nice and had maid service!
Next we graduated to two connecting rooms some trips in a moderate, some in a deluxe...whatever the budget could afford. The biggest advantage is TWO BATHROOMS, and it's nice to have the extra room to spread out.
Once we tried the Poly and Beach Club when one of the kids didn't go with us. I wouldn't want to do the Beach Club with six, even if one is under two, but the Poly rooms are hugh and space really wouldn't be an issue. It's just everyone in the same room again.
My personal favorite, since I really don't like seeing a washer/dryer or kitchen while on vacation, is to have two connecting rooms.
Just another opinion. Have fun planning!