As I start to compose this, it's 16:52 on Saturday here. 2 adults and 2 teenagers in the house. Moving into Autumn, outside air temp is about 21 C, no need for air-con atm (don't have it, anyway). Current loads: 2 laptops, 1 desktop, some household lighting (mix of halogen and CFL), I just heard the refrigerator switch on, maybe the freezer is also going. The charge controller remote display in the kitchen says the load is 19.1 amps - that's a combination of 4.1 amps @ 24VDC, and 15 amps of 240VAC - the household lighting circuit is 24VDC and runs directly off the batteries. 240 VAC comes from a sine-wave inverter. That 15a of 240v represents the 24 volt DC load, not 15*240=3600w as you might assume, so it's about 1.5 amps of AC (lets leave out conversion efficiencies for the sake of this discussion).
So the total load on the batteries right now of 19.1 amps at (currently) 24.8 volts DC gives a result of ~473 watts.
That's pretty close to your calculation. Load will go up as more lights go on, but otherwise will stay pretty stable until we all go to bed. I *might* have to run the generator for a bit later on if we decide to turn on the big-screen TV to watch something during/after dinner.
There's a couple of things that help to keep the load down. The inverter has a limit of 1500 watts continuous, any higher and there's a time limit ranging from ~1 hour @ 1600 w, to 30 seconds @ 3000 w. So we can't just have everything on at the same time. When it's time to do the vacuuming, all the computers have to go to sleep, and so on. There's no electric heating elements - no electric hot water, no electric jug, no electric toaster, no electric stove/oven, no electric clothes dryer (that one has to run directly off the generator when it's needed)
We have generally fine weather here, so the clothes dryer doesn't get used very often - we hang the wet clothes on the line outdoors.
We cook on a wood-fired stove (with a gas backup), which also heats our hot water, and about 40% of the firewood comes from own plot - grown, harvested and dried on the property.
Come and visit - I'll talk you into boredom about off-grid living :-)