Hi FlyF,
One of the first things I tell folks that are looking at off-grid, is to lower their expectations ;>]. What I mean is start by reducing the electrical loads any/every way possible. So, no electric heat or hot water, unless it it is thru load diversion (possibly/modestly with heat pumps). If you can provide those tasks with wood, LP or solar that lops off the (typically) biggest residential loads. Think LED lights, and not just good, but the very most efficient appliances you can find/buy. Reduce as much as practical the size of the refrigeration needed. I sometimes talk with folks who are smug about their new EE frig, but you could park a car in it, and it is only EE
relative to comparable's of the same size. Hang clothes; ditch the AC if possible. If you focus on those details, you can scale down the battery requirement quite a bit.
I otherwise agree with most of the comments. We try to 'make hay when the sun shines', so laundry, concerted cleaning, shop work... we try to do more on sunny/windy days.
We've also had real good results with load diversion. If you can use charge controllers that have that feature it makes it easier. Midnite Solar is one example. So, batteries get full... okay lets tuck some of that otherwise lost energy into water preheating dhw, or similar loads. Storing Btu's can be cheaper than batteries.
All that said, I recommend as robust a bank as you can afford. We have a family of five, and our bank is 1,200 AHrs @48V, or about 30 kWh at 50% DOD. Batteries are a major investment, and at best might last 15-ys (lead-acid). The cycle life vs. DOD looks like this for ours: